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%% ****** Start of file authguide.tex ****** %  %%  %% This file is part of the APS files in the REVTeX 4 distribution.  %% Version 4.1r of REVTeX, August 2010  %%  %% Copyright (c) 2009, 2010 The American Physical Society.  %%  %% See the REVTeX 4.1 README file for restrictions and more information.  %%  \listfiles  \documentclass[%  ,aps%  ,twocolumn%  ,secnumarabic%  ,amssymb, amsmath,nobibnotes, aps, prl, floatfix]{revtex4-1}  \usepackage{docs}%  \usepackage{bm}%  %\usepackage[colorlinks=true,linkcolor=blue]{hyperref}%  %\nofiles  \expandafter\ifx\csname package@font\endcsname\relax\else  \expandafter\expandafter  \expandafter\usepackage  \expandafter\expandafter  \expandafter{\csname package@font\endcsname}%  \fi  \begin{document}  \title{\revtex~4.1 Author's Guide}%  \author{American Physical Society}%  \email{[email protected]}  \affiliation{1 Research Road, Ridge, NY 11961}  \date{August 2010}%  \maketitle  \tableofcontents  \clearpage  \section{Introduction}  This is the author's guide to \revtex~4.1, the preferred submission  format for all APS and AIP journals. This guide is intended to be a concise  introduction to \revtex~4.1. The documentation has been separated out  into smaller units to make it easier to locate essential  information.  The following documentation is also part of the \revtex~4.1  distribution. Updated versions of these will be maintained at  the \revtex~4.1 homepage located at \url{http://authors.aps.org/revtex4/}.  \begin{itemize}  \item \textit{APS Author Guide for \revtex~4.1}  \item \textit{Author's Guide to AIP Substyles for \revtex~4.1}  \item \textit{\revtex~4.1 Command and Options Summary}  \item \textit{What's New in \revtex~4.1}  \end{itemize}  This guide assumes a working \revtex~4.1  installation. Please see the installation instructions included with the  distribution.  \subsection{Changes in \revtex~4.1}  The \revtex\ system for \LaTeX\ began its development in 1986 and has  gone through three major revisions since then. \revtex~4 was released in August, 2001. Since that time,  many user requests for new features were received. The main goals for \revtex~4.1 are to incorporate  this user feedback and provide support for the journals of the American Institute of Physics (AIP) . It incorporates the following changes:  \begin{itemize}  \item \textbf{Added support for APS journal \textit{Physical Review Special Topics -- Physics Education Research}}.  \item \textbf{Added support for AIP journals.} There is now an explicit \texttt{aip} society option along with support for AIP journals. Please see the \textit{Author's Guide to AIP Substyles for \revtex~4.1}. In addition, \revtex~4.1 provides an extensible system for the easy addition of new collections of journals.  \item \textbf{Endnotes now ordered correctly.} Endnotes in the bibliography now appear in the correct order, interleaved with citations.  \item \textbf{Multiple references in a single citation supported using a special starred (*) argument to the \cmd\cite\ command.} One of the major new features in 4.1 made possible by the joint work on \texttt{natbib 8.3}. Multiple Bib\TeX\ entries can be combined into a single \cmd\bibitem\ command.  \item \textbf{Free form text can be prepended and appended to a bibliographic entry using the special starred (*) argument to the \cmd\cite\ command.} Often a citation in the bibliography will have explanatory text such as \textit{See also} or \textit{and references therein} before and after the actual citation. The new \revtex~4.1 \cmd\cite\ command allows the specification of both text to precede and follow a citation.  \item \textbf{Structured Abstracts.} Use of the \texttt{description} environment in abstracts now provides for ``structured" abstracts.  \item \textbf{Figures referring to videos now supported.} A ``figure" may now be labeled as a \textbf{Video} by using the \texttt{video} environment. A frame from the video may be included in the figure and a URL to link the caption's label to the online video also may be included. There is also a \cmd\listofvideos\ command.  \item \textbf{Better support for arXiv.org in Bib\TeX\ } Three more Bib\TeX\ fields have been added: \texttt{SLACcitation}, \texttt{archivePrefix}, and \texttt{primaryClass} in addition to the existing field \texttt{eprint}.   \item \textbf{Improved Bib\TeX\ \texttt{bst} files.} In addition to the new features above, numerous other improvements to the APS \texttt{bst} files have been made, including support for displaying journal article titles (using the new \texttt{longbibliography} option) and many fixes for \textit{Reviews of Modern Physics}. Also, long author lists are no longer automatically truncated.  \item \textbf{\cmd\footnote\ in \cmd\widetext\ and \texttt{table*} environments improved.} \cmd\footnote\relax s in the \cmd\widetext\ or \texttt{table*} environments are now correctly placed and formatted.  \item \textbf{Email addresses no longer print twice on papers less than one page long.}  \item \textbf{\texttt{eqnarray} alignment improved.}  \item \textbf{\cmd\collaboration\ can be used with the \texttt{groupedaddress} option now.}  \item \textbf{\texttt{letterpaper} now ensured as default paper size.}   \item \textbf{Table of Contents formatting improved.}  \item \textbf{Support for the \texttt{longtable} package improved.}  \item \textbf{\texttt{reftest} restored.}  \item \textbf{Compatibility with the \texttt{geometry, lineno, lscape} and \texttt{colortbl} packages improved.} For line numbering, rather than using \texttt{lineno.sty} directly, the \texttt{linenumbers} class option should be used (this will call in \texttt{lineno.sty} with a proper set of default parameters).  \item \texttt{hyperref} \textbf{fixes}. Improvements were to make footnotes work better with the \texttt{hyperref} package. In particular, table footnotes were fixed. More anchors for \texttt{hyperref} were also added (titlepage, abstract, and acknowledgements).  \item \textbf{Documents can have more than 256 \cmd\cite\ commands now.}  \item \textbf{\cmd\listoffigures\ and \cmd\listoftables\ fixed.}  \item \textbf{Figure and table labels in captions now reflect proper APS style.}  \item \textbf{RMP style files conform better to RMP style guidelines.}  \item \textbf{Section heading upper-casing improved.}  \item \textbf{Repeated characters at start of affiliation no longer disappear when using \texttt{groupedaddress} option.}  \item \textbf{There have been many other bug fixes and improvements to the internal \texttt{ltxgrid} package as well.}  \end{itemize}  \subsection{\revtex~4 Backwards Compatibility}  Documents prepared under \revtex~4 should process correctly under \revtex~4.1. However, the formatting of the pages and, if using Bib\TeX, the references may change.  \subsection{Submitting to APS Journals}  Authors using \revtex~4.1 to prepare a manuscript for submission to  \textit{Physical Review Letters}, \textit{Physical Review}, \textit{Reviews of Modern Physics},   or other APS journals must also read the companion document \textit{APS Author Guide for \revtex~4.1}  distributed with \revtex\ and follow the guidelines detailed there.  The \revtex~4.1 distribution includes both a template  (\file{apstemplate.tex}) and a sample document (\file{apssamp.tex}).  The template is a good starting point for a manuscript. In the  following sections are instructions that should be sufficient for  creating a paper using \revtex~4.1.  Further information about submissions to the American  Physical Society may be found at \url{http://publish.aps.org/}.  \subsection{Submitting to AIP Journals}  \revtex~4.1 includes support for the journals of the American Institute of Physics.  The style files and authoring guides for these journals are distributed as part  \revtex~4.1 distribution. The distribution includes both a template  (\file{aiptemplate.tex}) and a sample document (\file{aipsamp.tex}).  The template is a good starting point for a manuscript. In the  following sections are instructions that should be sufficient for  creating a paper using \revtex~4.1.  More information may be found at   \url{http://www.aip.org/pubservs/compuscript.html}. Please consult the \textit{Author's Guide to AIP Substyles for \revtex~4.1} for more information about submissions to AIP journals, AIP styles files, and other AIP-specific information.  \subsection{Contact Information}\label{sec:aipresources}%  Any bugs, problems, or inconsistencies with \revtex\ or the APS journal style files should be reported to  \revtex\ support at \[email protected]+. Reports should include information on the error and a \textit{small}  sample document that manifests the problem if possible (please don't send large files!). Issues related to the AIP journal styles should be sent directly to \[email protected]+.  \section{Some \LaTeXe\ Basics}  \revtex~4.1 must sometimes patch the underlying  \LaTeX\ kernel. This means that \revtex~4.1 requires a fairly recent version of  \LaTeXe. Versions prior to 2005/12/01 may not work  correctly. \revtex~4.1 will be maintained to be compatible with future  versions of \LaTeXe.  \subsection{Useful \LaTeXe\ Markup}  \LaTeXe\ markup is the preferred way to accomplish many basic tasks.  \subsubsection{Fonts}  Because \revtex~4.1 is based upon \LaTeXe, it inherits all of the  macros used for controlling fonts. Of particular importance are the  \LaTeXe\ macros \cmd{\textit}, \cmd{\textbf}, \cmd{\texttt} for changing to  an italic, bold, or typewriter font respectively. One should always  use these macros rather than the lower-level \TeX\ macros \cmd{\it},  \cmd{\bf}, and \cmd{\tt}. The \LaTeXe\ macros offer  improvements such as better italic correction and scaling in super-  and subscripts for example. Table~\ref{tab:fonts}  summarizes the font selection commands in \LaTeXe.  \begin{table}  \caption{\label{tab:fonts}\LaTeXe\ font commands}  \begin{ruledtabular}  \begin{tabular}{ll}  \multicolumn{2}{c}{\textbf{Text Fonts}}\\  \textbf{Font command} & \textbf{Explanation} \\  \cmd\textit\marg{text} & Italics\\  \cmd\textbf\marg{text} & Boldface\\  \cmd\texttt\marg{text} & Typewriter\\  \cmd\textrm\marg{text} & Roman\\  \cmd\textsl\marg{text} & Slanted\\  \cmd\textsf\marg{text} & Sans Serif\\  \cmd\textsc\marg{text} & Small Caps\\  \cmd\textmd\marg{text} & Medium Series\\  \cmd\textnormal\marg{text} & Normal Series\\  \cmd\textup\marg{text} & Upright Series\\  &\\  \multicolumn{2}{c}{\textbf{Math Fonts}}\\  \cmd\mathit\marg{text} & Math Italics\\  \cmd\mathbf\marg{text} & Math Boldface\\  \cmd\mathtt\marg{text} & Math Typewriter\\  \cmd\mathsf\marg{text} & Math Sans Serif\\  \cmd\mathcal\marg{text} & Calligraphic\\  \cmd\mathnormal\marg{text} & Math Normal\\  \cmd\bm\marg{text}& Bold math for Greek letters\\  & and other symbols\\  \cmd\mathfrak\marg{text}\footnotemark[1] & Fraktur\\  \cmd\mathbb\marg{text}\footnotemark[1] & Blackboard Bold\\  \end{tabular}  \end{ruledtabular}  \footnotetext[1]{Requires \classname{amsfonts} or \classname{amssymb} class option}  \end{table}  \subsubsection{User-defined macros}  \LaTeXe\ provides several macros that enable users to easily create new  macros for use in their manuscripts:  \begin{itemize}  \footnotesize  \item \cmd\newcommand\marg{\\command}\oarg{narg}\oarg{opt}\marg{def}   \item \cmd\newcommand\verb+*+\marg{\\command}\oarg{narg}\oarg{opt}\marg{def}  \item \cmd\renewcommand\marg{\\command}\oarg{narg}\oarg{opt}\marg{def}  \item \cmd\renewcommand\verb+*+\marg{\\command}\oarg{narg}\oarg{opt}\marg{def}  \item \cmd\providecommand\marg{\\command}\oarg{narg}\oarg{opt}\marg{def}  \item \cmd\providecommand\verb+*+\marg{\\command}\oarg{narg}\oarg{opt}\marg{def}  \end{itemize}  Here \meta{\\command} is the name of the macro being defined,  \meta{narg} is the number of arguments the macro takes,  \meta{opt} are optional default values for the arguments, and  \meta{def} is the actually macro definiton. \cmd\newcommand\ creates a  new macro, \cmd\renewcommand\ redefines a previously defined macro,  and \cmd\providecommand\ will define a macro only if it hasn't  been defined previously. The *-ed versions are an optimization that  indicates that the macro arguments will always be ``short'' arguments. This is  almost always the case, so the *-ed versions should be used whenver  possible.  The use of these macros is preferred over using plain \TeX's low-level  macros such as  \cmd\def{},\cmd\edef{}, and \cmd\gdef{}. APS authors must follow the  \textit{APS Author Guide for \revtex~4.1} when defining macros.  \subsubsection{Symbols}  \LaTeXe\ has added some convenient commands for some special symbols  and effects. These are summarized in Table~\ref{tab:special}. See  \cite{Guide} for details.  \begin{table}  \caption{\label{tab:special}\LaTeXe\ commands for special symbols and effects}  \begin{ruledtabular}  \begin{tabular}{lc}  Command & Symbol/Effect\\  \cmd\textemdash & \textemdash\\  \cmd\textendash & \textendash\\  \cmd\textexclamdown & \textexclamdown\\  \cmd\textquestiondown & \textquestiondown\\  \cmd\textquotedblleft & \textquotedblleft\\  \cmd\textquotedblright & \textquotedblright\\  \cmd\textquoteleft & \textquoteleft\\  \cmd\textquoteright & \textquoteright\\  \cmd\textbullet & \textbullet\\  \cmd\textperiodcentered & \textperiodcentered\\  \cmd\textvisiblespace & \textvisiblespace\\  \cmd\textcompworkmark & Break a ligature\\  \cmd\textcircled\marg{char} & Circle a character\\  \end{tabular}  \end{ruledtabular}  \end{table}  \LaTeXe\ provides additional symbols in a  separate package called \classname{latexsym}. To use these symbols, include  the package using:  \begin{verbatim}  \usepackage{latexsym}  \end{verbatim}  \subsection{Using \LaTeXe\ packages with \revtex}\label{sec:usepackage}%  Many \LaTeXe\ packages are available, for instance, on CTAN at  \url{http://www.ctan.org/tex-archive/macros/latex/required/}  and at  \url{http://www.ctan.org/tex-archive/macros/latex/contrib/}  or may be available on other distribution media, such as the \TeX\  Live CD-ROM \url{http://www.tug.org/texlive/}. Some of these packages  are automatically loaded by \revtex~4.1 when certain class options are  invoked and are, thus, ``required.'' They will either be distributed  with \revtex\ or are already included with a standard \LaTeXe\  distribution.  Required packages are automatically loaded by \revtex\ on an as-needed  basis. Other packages should be loaded using the  \cmd\usepackage\ command. To load the  \classname{hyperref} package, the document preamble might look like:  \begin{verbatim}  \documentclass{revtex}  \usepackage{hyperref}  \end{verbatim}  Some common (and very useful) \LaTeXe\ packages are \textit{a priori}  important enough that \revtex~4.1 has been designed to be specifically  compatible with them.   A bug stemming from the use of one of these packages in  conjunction with any of the APS journals may be reported by contacting  \revtex\ support.  \begin{description}  \item[\textbf{AMS packages}] \revtex~4.1 is compatible with and depends  upon the AMS packages  \classname{amsfonts},  \classname{amssymb}, and  \classname{amsmath}. In fact, \revtex~4.1 requires use of these packages  to accomplish some common tasks. See Section~\ref{sec:math} for more.  \revtex~4.1 requires version 2.0 or higher of the AMS-\LaTeX\ package.  \item[\textbf{array and dcolumn}]  The \classname{array} and \classname{dcolumn} packages are part of  \LaTeX's required suite of packages. \classname{dcolumn} is required  to align table columns on decimal points (and it in turn depends upon  the \classname{array} package).  \item[\textbf{longtable}]  \file{longtable.sty} may be used for large tables that will span more than one  page. \revtex~4.1 dynamically applies patches to longtable.sty so that  it will work in two-column mode.  \item[\textbf{hyperref}] \file{hyperref.sty} is a package by Sebastian Rahtz that is  used for putting hypertext links into \LaTeXe\ documents.  \revtex~4.1 has hooks to allow e-mail addresses and URL's to become  hyperlinks if \classname{hyperref} is loaded.  \item[\textbf{lineno}] \revtex~4.1 improves compatibility with \classname{lineno.sty}. This package should only be loaded via the new \classoption{linenumbers} class option. See Section~\ref{sec:lineno} for more information.  \item[\textbf{lscape}] \revtex~4.1 improves compatibility with \classname{lscape.sty}.  \item[\textbf{geometry}] \revtex~4.1 improves compatibility with \classname{geometry.sty}.  \item[\textbf{colortbl}] \revtex~4.1 improves compatibility with \classname{colortbl.sty}.  \end{description}  Other packages will conflict with \revtex~4.1 and should be  avoided. Usually such a conflict arises because the package adds  enhancements that \revtex~4.1 already includes. Here are some common  packages that clash with \revtex~4.1:  \begin{description}  \item[\textbf{multicol}] \file{multicol.sty} is a package by Frank Mittelbach  that adds support for multiple columns. In fact, early versions of  \revtex~4.1 used \file{multicol.sty} for precisely this. \revtex~4.1   incorporates its own support for multiple-column typesetting.  \item[\textbf{cite}] Donald Arseneau's \file{cite.sty} is often used to provide  support for sorting a \cmd\cite\ command's arguments into numerical  order and to collapse consecutive runs of reference numbers. \revtex~4.1  has this functionality built-in already via the \classname{natbib} package.  \item[\textbf{mcite}] \revtex~4.1 already contains a lot of this  functionality through its updated syntax for the \cmd\cite\ command and  the latest \classname{natbib} package.  \item[\textbf{endfloat}] The same functionality can be accomplished  using the \classoption{endfloats} class option.  \item[\textbf{float}] \texttt{float.sty} provides a mechanism for creating new float classes with just a few commands. \revtex~4.1 has limited compatible with float.sty. If attempting to use this package, be sure to put any \cmd\newfloat\ commands after the \verb+\begin{document}+ line.  \end{description}  \section{The Document Preamble}  The preamble of a \LaTeX\ document is the set of commands that precede  the \envb{document} line. It contains a  \cmd\documentclass\ line to load the \revtex~4.1 class (\textit{i.e.},  all of the \revtex~4.1 macro definitions), \cmd\usepackage\ macros to  load other macro packages, and other macro definitions.  \subsection{The \emph{documentclass} line}  The basic formatting of the manuscript is controlled by setting  \emph{class options} using  \cmd\documentclass\oarg{options}\aarg{\classname{revtex4-1}}.  The optional arguments that appear in the square brackets control the layout of the  document. At this point, one only needs to choose:  \begin{itemize}  \item Either the \classoption{aps} (default) or \classoption{aip} society option  \item One of the chosen society's journal styles such as \classoption{prl} or \classoption{apl}  \item A layout option such as \classoption{preprint} (single-column formatting), \classoption{reprint} (an approximation  to the selected journal's actual layout which may be one- or two-column depending on the journal), or \classoption{twocolumn}  \end{itemize}  Usually, one would want to use \classoption{preprint} for draft papers. Paper size options are also  available as well. In particular, \classoption{a4paper} is available  as well as the rest of the standard \LaTeX\ paper sizes. A  full list of class options is given in the \textit{\revtex~4.1 Command  and Options Summary}.  \subsection{Loading other packages}  Other packages may be loaded into a \revtex~4.1 document by using the  standard \LaTeXe\ \cmd\usepackage\ command. For instance, to load  the \classoption{graphics} package, one would use  \verb+\usepackage{graphics}+.  \section{The Front Matter}\label{sec:front}  After choosing the basic look and feel of the document by selecting  the appropriate class options and loading in whatever other macros are  needed, one is ready to move on to creating a new manuscript. After  the preamble, be sure to put in a \envb{document} line (and put  in an \enve{document} as well). This section describes the macros  \revtex~4.1 provides for formatting the front matter of the  article. The behavior and usage of these macros can be quite  different from those provided in the \LaTeXe\ \classname{article} class.  \subsection{Setting the title}  The title of the manuscript is simply specified by using the  \cmd\title\aarg{title} macro. A \verb+\\+ may be used to put a line  break in a long title.  \subsection{Specifying a date}%  The \cmd\date\marg{date} command outputs the date on the  manuscript. Using \cmd\today\ will cause \LaTeX{} to insert the  current date whenever the file is run:  \begin{verbatim}  \date{\today}  \end{verbatim}  \subsection{Specifying authors and affiliations}  The \revtex~4.1 macros for specifying authors and their affiliations are designed  to save labor for authors and during production. Authors and affiliations are  arranged into groupings called, appropriately enough, \emph{author  groups}. Each author group is a set of authors who share the same set  of affiliations. Author names are specified with the \cmd\author\  macro while affiliations (or addresses) are specified with the  \cmd\affiliation\ macro. Author groups are specified by sequences of  \cmd\author\ macros followed by \cmd\affiliation\ macros. An  \cmd\affiliation\ macro applies to all previously specified  \cmd\author\ macros which don't already have an affiliation supplied.  For example, if Bugs Bunny and Roger Rabbit are both at Looney Tune  Studios, while Mickey Mouse is at Disney World, the markup would be:  \begin{verbatim}  \author{Bugs Bunny}  \author{Roger Rabbit}  \affiliation{Looney Tune Studios}  \author{Mickey Mouse}  \affiliation{Disney World}  \end{verbatim}  The default is to display this as   \begin{center}  Bugs Bunny and Roger Rabbit\\  \emph{Looney Tune Studios}\\  Mickey Mouse\\  \emph{Disney World}\\  \end{center}  This layout style for displaying authors and their affiliations is  chosen by selecting the class option  \classoption{groupedaddress}. Journal styles usually default this option,  so it need not be specified explicitly. The other major way of displaying this  information is to use superscripts on the authors and  affiliations. This can be accomplished by selecting the class option  \classoption{superscriptaddress}. To achieve the display  \begin{center}  Bugs Bunny,$^{1}$ Roger Rabbit,$^{1,2}$ and Mickey Mouse$^{2}$\\  \emph{$^{1}$Looney Tune Studios}\\  \emph{$^{2}$Disney World}\\  \end{center}  one would use the markup  \begin{verbatim}  \author{Bugs Bunny}  \affiliation{Looney Tune Studios}  \author{Roger Rabbit}  \affiliation{Looney Tune Studios}  \affiliation{Disney World}  \author{Mickey Mouse}  \affiliation{Disney World}  \end{verbatim}  Note that \revtex~4.1 takes care of any commas and \emph{and}'s that join  the author names together and font selection, as well as any  superscript numbering. Only the author names and affiliations should  be given within their respective macros. See below for further information  regarding the proper way to add footnotes to author names and affiliations.  There is a third class option, \classoption{unsortedaddress}, for  controlling author/affiliation display. The default  \classoption{groupedaddress} will actually sort authors into the  approriate author groups if one chooses to specify an affiliation for  each author. The markup:  \begin{verbatim}  \author{Bugs Bunny}  \affiliation{Looney Tune Studios}  \author{Mickey Mouse}  \affiliation{Disney World}  \author{Roger Rabbit}  \affiliation{Looney Tune Studios}  \end{verbatim}  will result in the same display as for the first case given  above even though Roger Rabbit is specified after Mickey Mouse. To  avoid Roger Rabbit being moved into the same author group as Bugs  Bunny, use the  \classoption{unsortedaddress} option instead. In general, it is safest  to list authors in the order they should appear and specify  affiliations for multiple authors rather than one at a time. This will  afford the most independence for choosing the display option. Finally,  it should be mentioned that the affiliations for the  \classoption{superscriptaddress} are presented and numbered   in the order that they are encountered. These means that the order  will usually follow the order of the authors. An alternative ordering  can be forced by including a list of \cmd\affiliation\ commands before  the first \cmd{\author} in the desired order. Then use the exact same  text for each affilation when specifying them for each author.  If an author doesn't have an affiliation, the \cmd\noaffiliation\  macro may be used in the place of an \cmd\affiliation\ macro.  \subsubsection{Collaborations}  A collaboration name can be specified with the \cmd\collaboration\  command. This is very similar to the \cmd\author\ command. In \revtex~4.1, it can  be used with both the \classoption{superscriptaddress} and \classoption{groupedaddress} class options. The  \cmd\collaboration\ command should appear at the end of the list of  authors. The collaboration name will be appear centered in parentheses  between the list of authors and the list of  affiliations. Because collaborations  don't normally have affiliations, one needs to follow the  \cmd\collaboration\ with \cmd\noaffiliation.  \subsubsection{Footnotes for authors, collaborations, affiliations or title}\label{sec:footau}  Often one wants to specify additional information associated with an  author, collaboration, or affiliation such as an e-mail address, an  alternate affiliation, or some other ancillary information.   \revtex~4.1 introduces several new macros just for this purpose. They  are:  \begin{itemize}  \item\cmd\email\oarg{optional text}\aarg{e-mail address}  \item\cmd\homepage\oarg{optional text}\aarg{URL}  \item\cmd\altaffiliation\oarg{optional text}\aarg{affiliation}  \item\cmd\thanks\aarg{miscellaneous text}  \end{itemize}  In the first three, the \emph{optional text} will be prepended before the  actual information specified in the required argument. In the APS journal style files, \cmd\email\ and \cmd\homepage\ no longer have a default value. However, in the AIP styles, each have a default text for their optional arguments  (`Electronic address:' and `URL:' respectively). The \cmd\thanks\  macro should only be used if one of the other three do not apply. Any  author name can have multiple occurences of these four macros. Note  that unlike the  \cmd\affiliation\ macro, these macros only apply to the \cmd\author\  that directly precedes it. Any \cmd\affiliation\ \emph{must} follow  the other author-specific macros. A typical usage might be as follows:  \begin{verbatim}  \author{Bugs Bunny}  \email[E-mail me at: ]{[email protected]}  \homepage[Visit: ]{http://looney.com/}  \altaffiliation[Permanent address: ]  {Warner Brothers}  \affiliation{Looney Tunes}  \end{verbatim}  This would result in the footnote ``E-mail me at: \texttt{[email protected]},  Visit: \texttt{http://looney.com/}, Permanent address: Warner  Brothers'' being attached to Bugs Bunny. Note that:  \begin{itemize}  \item Only an e-mail address, URL, or affiliation should go in the  required argument in the curly braces.  \item The font is automatically taken care of.  \item An explicit space is needed at the end of the optional text if one is  desired in the output.  \item Use the optional arguments to provide customized  text only if there is a good reason to.  \end{itemize}  The \cmd\collaboration\ , \cmd\affiliation\ , or even \cmd\title\ can  also have footnotes attached via these commands. If any ancillary data  (\cmd\thanks, \cmd\email, \cmd\homepage, or  \cmd\altaffiliation) are given in the wrong context (e.g., before any  \cmd\title, \cmd\author, \cmd\collaboration, or \cmd\affiliation\  command has been given), then a warning is given in the \TeX\ log, and  the command is ignored.  Duplicate sets of ancillary data are merged, giving rise to a single  shared footnote. However, this only applies if the ancillary data are  identical: even the order of the commands specifying the data must be  identical. Thus, for example, two authors can share a single footnote  indicating a group e-mail address.  Duplicate \cmd\affiliation\ commands may be given in the course of the  front matter, without the danger of producing extraneous affiliations  on the title page. However, ancillary data should be specified for  only the first instance of any particular institution's  \cmd\affiliation\ command; a later instance with different ancillary  data will result in a warning in the \TeX\ log.  It is preferable to arrange authors into  sets. Within each set all the authors share the same group of  affiliations. For each author, give the \cmd\author\ (and appropriate  ancillary data), then follow this author group with the needed group  of \cmd\affiliation\ commands.  If affiliations have been listed before the first  \cmd\author\ macro to ensure a particular ordering, be sure  that any later \cmd\affiliation\ command for the given institution is  an exact copy of the first, and also ensure that no ancillary data is  given in these later instances.  Each journal class option has a default behavior for the placement of these  ancillary information footnotes. For instance, the \classoption{prb} option puts all  such footnotes at the start of the bibliography while the \classoption{prl}  journal styles displays them on the first page. One can override a  journal style's default behavior by specifying explicitly the class  option  \classoption{bibnotes} (puts the footnotes at the start of the  bibliography) or \classoption{nobibnotes} (puts them on the first page).  Please consult the documentation for the various journal style files for further information.  \subsubsection{Specifying first names and surnames}  Many authors have names in which either the surname appears first  or in which the surname is made up of more than one name. To ensure  that such names are accurately captured for indexing and other  purposes, the \cmd\surname\ macro should be used to indicate which portion  of a name is the surname. Similarly, there is a \cmd\firstname\ macro  as well, although usage of \cmd\surname\ should be sufficient. If an  author's surname is a single name and written last, it is not  necessary to use these macros. These macros do nothing but indicate  how a name should be indexed. Here are some examples:  \begin{verbatim}  \author{Andrew \surname{Lloyd Weber}}  \author{\surname{Mao} Tse-Tung}  \end{verbatim}  \subsection{The abstract}  An abstract for a paper is specified by using the \env{abstract}  environment:  \begin{verbatim}  \begin{abstract}  Text of abstract  \end{abstract}  \end{verbatim}  Note that in \revtex~4.1 the abstract must be specified before the  \cmd\maketitle\ command and there is no need to embed it in an explicit  minipage environment.  \subsubsection{Structured abstracts}  A new feature in \revtex~4.1 is support for \textit{structured abstracts}. A ``structured" abstract is an abstract divided into labeled sections. For instance, \textit{Physical Review C} would like authors to provide abstracts with sections summarizing the paper's \textbf{Background}, \textbf{Purpose}, \textbf{Method}, \textbf{Results}, and \textbf{Conclusions}. This can be accomplished by using the \texttt{description} environment within the \texttt{abstract} environment. For example:  \begin{verbatim}  \begin{abstract}  \begin{description}  \item[Background] This part would describe the  context needed to understand what the paper  is about.  \item[Purpose] This part would state the purpose  of the present paper.  \item[Method] This part describe the methods  used in the paper.  \item[Results] This part would summarize the  results.  \item[Conclusions] This part would state the  conclusions of the paper.  \end{description}  \end{abstract}  \end{verbatim}  \subsection{PACS codes}  APS and AIP authors are asked to supply suggested PACS codes with their  submissions. The \cmd\pacs\ macro is provided as a way to do this:  \begin{verbatim}  \pacs{23.23.+x, 56.65.Dy}  \end{verbatim}  The actual display of the PACS numbers below the abstract is  controlled by two class options: \classoption{showpacs} and  \classoption{noshowpacs}. In particular, this is now independent of  the \classoption{preprint} option. \classoption{showpacs} must be  explicitly included in the class options to display the PACS codes.  \subsection{Keywords}  A \cmd\keywords\ macro may also be used to indicate keywords for the  article.   \begin{verbatim}  \keywords{nuclear form; yrast level}  \end{verbatim}  This will be displayed below the abstract and PACS (if supplied). Like  PACS codes, the actual display of the the keywords is controlled by  two classoptions: \classoption{showkeys} and  \classoption{noshowkeys}. An explicit \classoption{showkeys} must be  included in the \cmd\documentclass\ line to display the keywords.  \subsection{Institutional report numbers}  Institutional report numbers can be specified using the \cmd\preprint\  macro. If the \classoption{preprintnumbers} class option is specified, these will be displayed in the upper right corner of the first page. Multiple \cmd\preprint\ macros maybe supplied (space is  limited though, so only three or less may actually fit). Please note that the \classoption{preprint} class option does not automatically invoke \classoption{preprintnumbers}.  \subsection{maketitle}  After specifying the title, authors, affiliations, abstract, PACS  codes, and report numbers, the final step for formatting the front  matter of the manuscript is to execute the \cmd\maketitle\ macro by  simply including it:  \begin{verbatim}  \maketitle  \end{verbatim}  The \cmd\maketitle\ macro must follow all of the macros listed  above. The macro will format the front matter in accordance with the various  class options that were specified in the  \cmd\documentclass\ line (either implicitly through defaults or  explicitly).  \section{The body of the paper}  For typesetting the body of a paper, \revtex~4.1 relies heavily on  standard \LaTeXe\ and other packages (particulary those that are part  of AMS-\LaTeX). Users unfamiliar with these packages should read the  following sections carefully.   \subsection{Section headings}  Section headings are input as in \LaTeX.  The output is similar, with a few extra features.  Four levels of headings are available in \revtex{}:  \begin{quote}  \cmd\section\marg{title text}\\  \cmd\subsection\marg{title text}\\  \cmd\subsubsection\marg{title text}\\  \cmd\paragraph\marg{title text}  \end{quote}  Use the starred form of the command to suppress the automatic numbering; e.g.,  \begin{verbatim}  \section*{Introduction}  \end{verbatim}  To label a section heading for cross referencing, best practice is to  place the \cmd\label\marg{key} within the argument specifying the heading:  \begin{verbatim}  \section{\label{sec:intro}Introduction}  \end{verbatim}  In some journal substyles, such as those of the APS,  all text in the \cmd\section\ command is automatically set uppercase.  If a lowercase letter is needed, use \cmd\lowercase\aarg{x}.  For example, to use ``He'' for helium in a \cmd\section\marg{title text} command, type  \verb+H+\cmd\lowercase\aarg{e} in \marg{title text}.  Use \cmd\protect\verb+\\+ to force a line break in a section heading.  (Fragile commands must be protected in section headings, captions, and  footnotes and \verb+\\+ is a fragile command.)  \subsection{Paragraphs and General Text}  Paragraphs always end with a blank input line. Because \TeX\  automatically calculates linebreaks and word hyphenation in a  paragraph, it is not necessary to force linebreaks or hyphenation. Of  course, compound words should still be explicitly hyphenated, e.g.,  ``author-prepared copy.''  Use directional quotes for quotation marks around quoted text  (\texttt{``xxx''}), not straight double quotes (\texttt{"xxx"}).  For opening quotes, use one or two backquotes; for closing quotes,  use one or two forward quotes (apostrophes).  \subsection{One-column vs. two-column layouts}\label{sec:widetext}  One of the hallmarks of \textit{Physical Review} and many of the AIP journals is their two-column  formatting. \revtex~4.1 provides the \classoption{reprint} class option that provides for each  journal class option a close approximation to the journal's actual production formatting. Note that  the \classoption{reprint} option will give either one or two-column formatting as appropriate for the particular journal.  For most APS and AIP journals, the \classoption{reprint} option will take care of formatting the front matter  (including the abstract) as a single column and will typeset the body in two columns. \revtex~4.1 has its own  built-in two-column formatting macros to provide well-balanced columns as well as reasonable control over the placement of floats in either  one- or two-column modes. When drafting papers, it is common to use a one-column format. This is best achieved by using the  \classoption{preprint} class option. Authors may override a particular journal's formatting by using the lower level options \classoption{onecolumn} and \classoption{twocolum}, but best practice is to stick with the \classoption{preprint} and \classoption{reprint} options.  Please note that the \classoption{reprint} class option is only an \textit{approximation} of a journal's final layout. Because of font differences, figure rescaling, and other factors, authors should not expect the \classoption{reprint} option to give fully accurate estimates of an article's ultimate length after being typeset for the journal.  Occasionally it is necessary to change the formatting from two-column to  one-column to better accommodate very long equations that are more  easily read when typeset to the full width of the page. This is  accomplished using the \env{widetext} environment:  \begin{verbatim}  \begin{widetext}  long equation goes here  \end{widetext}  \end{verbatim}  In two-column mode, this will temporarily return to one-column mode,  balancing the text before the environment into two short columns, and  returning to two-column mode after the environment has  finished. \revtex~4.1 will also add horizontal rules to guide the  reader's eye through what may otherwise be a confusing break in the  flow of text. The  \env{widetext} environment has no effect on the output under the   \classoption{preprint} class option because this already uses  one-column formatting.  Use of the \env{widetext} environment should be restricted to the bare  minimum of text that needs to be typeset this way. However, short pieces  of paragraph text and/or math between nearly contiguous wide equations  should be incorporated into the surrounding wide sections.  Low-level control over the column grid can be accomplished with the  \cmd\onecolumngrid\ and \cmd\twocolumngrid\ commands. Using these, one  can avoid the horizontal rules added by \env{widetext}. These commands  should only be used if absolutely necessary. Wide figures and tables  should be accommodated using the proper \verb+*+ environments.  \subsection{Cross-referencing}\label{sec:xrefs}  \revtex{} inherits the \LaTeXe\ features for labeling and cross-referencing  section headings, equations, tables, and figures. This section  contains a simplified explanation of these cross-referencing features.  The proper usage in the context of section headings, equations,  tables, and figures is discussed in the appropriate sections.  Cross-referencing depends upon the use of ``tags,'' which are defined by  the user. The \cmd\label\marg{key} command is used to identify tags for  \revtex. Tags are strings of characters that serve to label section  headings, equations, tables, and figures that replace explicit,  by-hand numbering.  Files that use cross-referencing (and almost all manuscripts do)  need to be processed through \revtex\ at least twice to  ensure that the tags have been properly linked to appropriate numbers.  If any tags are added in subsequent editing sessions,   \LaTeX{} will display a warning message in the log file that ends with  \texttt{... Rerun to get cross-references right}.  Running the file through \revtex\ again (possibly more than once) will  resolve the cross-references. If the error message persists, check  the labels; the same \marg{key} may have been used to label more than one  object.  Another \LaTeX\ warning is \texttt{There were undefined references},  which indicates the use of a key in a \cmd\ref\ without ever  using it in a \cmd\label\ statement.  \revtex{} performs autonumbering exactly as in standard \LaTeX.  When the file is processed for the first time,  \LaTeX\ creates an auxiliary file (with the \file{.aux} extension) that   records the value of each \meta{key}. Each subsequent run retrieves  the proper number from the auxiliary file and updates the auxiliary  file. At the end of each run, any change in the value of a \meta{key}  produces a \LaTeX\ warning message.  Note that with footnotes appearing in the bibliography, extra passes  of \LaTeX\ may be needed to resolve all cross-references. For  instance, putting a \cmd\cite\ inside a \cmd\footnote\ will require at  least three passes.  Using the \classname{hyperref} package to create hyperlinked PDF files  will cause reference ranges to be expanded to list every  reference in the range. This behavior can be avoided by using the  \classname{hypernat} package available from \url{www.ctan.org}.  \subsection{Acknowledgments}  Use the \env{acknowledgments} environment for an acknowledgments  section. Depending on the journal substyle, this element may be  formatted as an unnumbered section title \textit{Acknowledgments} or  simply as a paragraph. Please note the spelling of  ``acknowledgments.''  \begin{verbatim}  \begin{acknowledgments}  The authors would like to thank...  \end{acknowledgments}  \end{verbatim}  \subsection{Appendices}  The \cmd\appendix\ command signals that all following sections are  appendices, so \cmd\section\marg{title text} after \cmd\appendix\ will set  \marg{title text} as an appendix heading (an empty \marg{title text}  is permitted). For a single appendix, use a  \cmd\appendix\verb+*+ followed by \cmd\section\marg{title text}  command to suppress the appendix letter in the section heading.  \subsection{\label{sec:lineno}Line numbering}  \revtex~4.1 provides the \classoption{linenumbers} class option to enable line numbering. While it is  possible to directly call in the \classname{lineno.sty}, using the class option ensures  that the default parameters needed to properly typeset the line numbers are set up correctly. It is  still possible for authors to override parameters such as \cmd\linenumbersep\ as usual, however.  \section{Math and equations}\label{sec:math}  \subsection{Math in text}  Not surprisingly, \revtex\ uses the \TeX\ math \verb+$+ delimiters  for math embedded in text. For example,  \verb|$a^{z}$| give $a^{z}$. Within math mode, use  \verb+^+\marg{math} for superscripts and  \verb+_+\marg{math} for subscripts. If the braces after the  \verb+^+ are omitted, \TeX{} will  superscript the next \emph{token} (generally a single character or  command). Thus it is safest to use explicit braces \verb+{}+.  As with text, math should not require extensive explicit vertical or  horzontal motion commands, because \TeX\ calculates math spacing  itself automatically. In particular, explicit spacing around  relations (e.g., $=$) or operators (e.g., $+$) should be  unnecessary. These suggestions notwithstanding, some fine-tuning of  math is required in specific cases, see Chapter~18 in the \TeX  book\cite{TeXbook}.  \subsection{Text in math}\label{sec:textinmath}  There are times when normal, non-italic text needs to be inserted  into a math expression. The \cmd\text\marg{text} command is the  preferred method of accomplishing this. It produces regular text  \emph{and} scales correctly in superscripts:  \verb+$y=x \text{ for } x_{\text{e-p}}$+ gives   ``$y=x \text{ for } x_{\text{e-p}}$''. To use the \cmd\text\ command,  the \classname{amsmath} package must be loaded: include a  \cmd\usepackage\aarg{\classname{amsmath}} command in the document  preamble or use the class option \classoption{amsmath}. Please note  that \revtex~4.1 requires version 2.0 or higher of \classname{amsmath}.  Other common alternatives may be less desirable. Using the standard  \LaTeXe\ \cmd\mbox\marg{text} will give normal text, including a hyphen,  but will not scale correctly in superscripts:  \verb+$x_{\mbox{e-p}}$+ gives ``$x_{\mbox{e-p}}$''.  The \cmd\rm\ command  only switches to Roman font for math letters. It does not, for  example, handle hyphens correctly:  \verb+$$x_{\rm{e-p}}$+ gives ``$x_{\rm e-p}$''. But note that  \cmd\textrm{}, it does work: \verb+$x_{\textrm{e-p}}$+ gives ``$x_{\textrm{e-p}}$''.  \subsection{Displayed equations}\label{sec:dispmath}  Equations are set centered in the column width or flush left depending  on the selected journal substyle.  For the simplest type of displayed equation, a numbered, one-line  equation, use the \env{equation} environment.  \revtex\ takes care of the equation number%  ---the number will be set below the equation if necessary.  Use \cmd\[\dots\cmd\] for a single, one-line unnumbered display equation.  Use the \env{eqnarray} environment when more than one consecutive  equation occurs, putting each equation in a separate row of the  environment, and using \cmd\nonumber\ before the row end (\cmd\\) to  suppress the equation number where necessary. If the equations are  related to each other, align each on the respective relation operator  (such as $=$).  When an equation is broken over lines or is continued over multiple  relation operators, it is called a multi-line or continued equation,  respectively; here, too, use the \env{eqnarray} environment.  For a continued equation, align each row on the relation operator just  as with multiple equations, and use the \cmd\nonumber\ command to  suppress auto-numbering on broken lines. Also, use the starred form  of the row end (\cmd\\\verb+*+) to prevent a pagebreak at that  juncture.  Short displayed equations that can appear together on a single line  separated by \cmd\qquad\ space may be placed in a single  \env{equation} environment.  As explained in Section~\ref{sec:widetext}, occasionally in two-column  mode a long equation, in order to fit it in the narrow column width,  would need to be broken into so many lines that it would affect  readibility. Set it in a wide column using the \env{widetext}  environment. Then return to the normal text width as soon as  possible.  The sample file \file{apssamp.tex} illustrates how to obtain each of  the above effects.  \subsection{Numbering displayed equations}  \revtex~4.1 automatically numbers equations.  For single-line and multi-line equations, use the  \env{equation} and \env{eqnarray} environments as described above.  For unnumbered single-line equations, use the \verb+\[+\dots\verb+\]+  construction. The command \cmd\nonumber\ will suppress the numbering  on a single line of an  \env{eqnarray}.  For a multi-line equation with no equation numbers at all,  use the \env{eqnarray*} environment.  A series of equations can be a labeled with a lettered sequence,  e.g., (3a), (3b), and (3c), by  putting the respective \env{equation} or \env{eqnarray} environment within a  \env{subequations} environment.   The \classname{amsmath} package (can be loaded with the  \classoption{amsmath} class option) is required for this.  Use the command \cmd\tag\marg{number} to produce an idiosyncratic  equation number: $(1')$, for example. Numbers assigned by \cmd\tag\  are completely independent of \revtex's automatic numbering. The  package \classname{amsmath} is required for using the \cmd\tag\  command. Please  note that the use of the \texttt{tag} command may conflict with the use of the \classoption{hyperref} package  due an incompatibility between \classoption{amsmath} and \classoption{hyperref}.   To have \revtex{} reset the equation numbers at the start of each section,  use the \classoption{eqsecnum} class option in the document preamble.   See the sample file \file{apssamp.tex} for some examples.  \subsection{Cross-referencing displayed equations}  To refer to a numbered equation, use  the \cmd\label\marg{key} and \cmd\ref\marg{key} commands.  The \cmd\label\marg{key} command is used within the referenced equation  (on the desired line of the \env{eqnarray}, if a multi-line equation):  \begin{verbatim}  \begin{equation}  A=B \label{pauli}  \end{equation}  ... It follows from Eq.~(\ref{pauli})  that this is the case ...  \begin{eqnarray}  A & = &B,\label{pauli2}\\  A'& = &B'  \end{eqnarray}  \end{verbatim}  gives   \begin{equation}  A=B \label{pauli}  \end{equation}  ... It follows from Eq.~(\ref{pauli})  that this is the case ...  \begin{eqnarray}  A & = &B,\label{pauli2}\\  A'& = &B'  \end{eqnarray}  Please note the parentheses surrounding the \cmd\ref\ command.  These are \emph{not} provided automatically and, thus, must be  explicitly incorporated.  Numbers produced with \cmd\tag\ can also be cross-referenced by adding  a \cmd\label\ command after the \cmd\tag\ command.  Using a \cmd\label\ after \envb{subequations} to reference the  \emph{general} number of the equations in the  \env{subequations} environment. For example, if  \begin{verbatim}  \begin{subequations}  \label{allequations} % notice location  \begin{eqnarray}  E&=&mc^2,\label{equationa}  \\  E&=&mc^2,\label{equationb}  \\  E&=&mc^2,\label{equationc}  \end{eqnarray}  \end{subequations}  \end{verbatim}  %  gives the output  \begin{subequations}  \label{allequations} % notice location  \begin{eqnarray}  E&=&mc^2,\label{equationa}  \\  E&=&mc^2,\label{equationb}  \\  E&=&mc^2,\label{equationc}  \end{eqnarray}  \end{subequations}  %  then \verb+Eq.~(\ref{allequations})+ gives ``Eq.~(\ref{allequations})''.  {\bf Note:} incorrect cross-referencing will result if  \cmd\label\ is used in an unnumbered single-line equation  (i.e., within the \verb+\[+ and \verb+\]+ commands),  or if \cmd\label\ is used on a line of an eqnarray that is not being numbered  (i.e., a line that has a \cmd\nonumber).  \subsection{Using the AMS packages \classoption{amsfonts},  \classoption{amssymb}, and \classoption{amsmath}}\label{AMS}  The American Mathematical Society's AMS-\LaTeX\ packages provided extra  fonts, symbols, and math markup that are quite convenient. \revtex~4.1  supports the use of these packages directly. To use the \classoption{amsfonts},  \classoption{amssymb}, and \classoption{amsmath} class options,  AMS-\LaTeX\ (and perhaps the additional AMS fonts) will need to be  installed. Please note that \revtex~4.1 requires version 2.0 or higher  of AMS-\LaTeX. These packages can be downloaded from  \url{http://www.ams.org/tex/}.  There are two class options for accessing the AMS fonts:  \classoption{amsfonts} and \classoption{amssymb}.  The \classoption{amsfonts} option defines the \cmd\mathfrak\ and  \cmd\mathbb\ commands to switch to the Fraktur and  Blackboard Bold fonts, respectively.  These fonts are selected with the \cmd\mathfrak\ and \cmd\mathbb\  font-switching commands:  \verb+${\mathfrak{G}}$+ gives a Fraktur ``$\mathfrak{G}$''  and \verb+${\mathbb{Z}}$+ gives a Blackboard Bold ``$\mathbb{Z}$''.  \revtex{} does not currently support the use of the extra Euler fonts  (the AMS fonts starting with \texttt{eur} or \texttt{eus}) or the  Cyrillic fonts (the AMS fonts starting with \texttt{w}).  The \classoption{amssymb} class option gives all the font  capabilities of the  \classoption{amsfonts} class option and further defines the commands  for many commonly used math symbols. These symbols will scale  correctly in superscripts and other places. See the AMS-\LaTeX\  documentation for the complete list of symbols available.  \subsection{Bold symbols in math}\label{sec:bboxamsfonts}  \revtex~4.1 uses the standard \LaTeXe\ Bold Math (\classname{bm}) package as the  basis for creating bold symbols in math mode. As usual, this requires  an explicit \cmd\usepackage\aarg{\classname{bm}} in the document  preamble. The command  \cmd\bm\marg{symbol} makes \marg{symbol} bold in math mode, ensuring  that it is the correct size, even in superscripts. If the correct font  in the correct size is not available then result is the \marg{symbol}  set at the  correct size in lightface and a \LaTeXe\ warning that says  ``\texttt{No boldmath typeface in this size}\dots''. Most bold special  characters will require that the AMS fonts be installed and the  \classoption{amsfonts} class option be invoked.  \cmd\bm\ is the proper means to get bold Greek characters---upper- and  lowercase---and other symbols.  The following will come out bold with \cmd\bm:  normal math italic letters, numbers,  Greek letters (uppercase and lowercase),  small bracketing and operators, and \cmd\mathcal. Fraktur  characters will come out bold in a \cmd\bm; however, Blackboard Bold  requires using the \cmd\mathbb\ command rather than \cmd{\bm}.  The \classoption{amsfonts} option adds support for bold math  letters and symbols in smaller sizes and in superscripts when a  \cmd\bm\marg{symbol} is used.   For example, \verb+$\pi^{\bm{\pi}}$+ gives a bold  lowercase pi in the superscript position: $^{\pi\bm{\pi}}$.  Note that \cmd\bm\marg{math} is a fragile command and, thus, should be  preceded by \cmd\protect\ in commands with moving arguments.  \section{Footnotes}  \LaTeX's standard \cmd\footnote\ command is available in  \revtex~4.1. The footnote text can either appear at the bottom of a page or  as part of the bibliography. This choice can be controlled by two class options:  \classoption{footinbib} and \classoption{nofootinbib}. \revtex~4.1  defaults to the former. Specific journal options may select a  different value than the default.  Please note that even if Bib\TeX\ is not being used for the references, you  may have to run Bib\TeX\ if you are using footnotes without the \classoption{nofootinbib} option.  The log file will contain errors about missing references such as \texttt{Note1} in this case and a file ending in  \texttt{Notes.bib} will have been produced during the processing of the \TeX\ file.  Note that in the latter case, the  argument of the  \cmd\footnote\ command is a moving argument in the sense of the \LUG,  Appendix~C.1.3: any fragile command within that argument must be  preceded by a \cmd\protect\ command.  The \cmd\footnote\ macro \emph{should not} be used in the front  matter for indicating author/affiliation relationships or to provide  additional information about authors (such as an e-mail  address). See Section~\ref{sec:footau} for the proper way to do  this.  Finally, footnotes that appear in tables behave differently. They  will be typeset as part of the table itself. See  Section~\ref{sec:tablenote} for details.  \section{Citations and References}\label{sec:endnotes}  \revtex~4.1 adds significant new functionality to \revtex~4's   typesetting of citations and references. The new functionality is  designed to make it easier to use Bib\TeX\ and produce the desired output   in the reference section without having to edit Bib\TeX's output. The new features include:  \begin{itemize}  \item Endnotes created with the \cmd\footnote\ command are automatically interleaved with the bibliographic references. \revtex~4 would typeset all endnotes at the end of the bibliography.  \item Combining multiple references automatically into a single entry in the bibliography. \revtex~4 required by-hand editing of Bib\TeX\ output. This is achieved by prepending an asterisk (*) to the reference's \textit{key} in the \cmd\cite\ command. \verb+\cite{{key1,*key2}+ would make a single entry in the bibliography by combining into one \cmd\bibitem\ the entries from the \texttt{.bib} file with keys \textit{key1} and \textit{key2}. See Section~\ref{sec:multiple} for more details.  \item Text can be prepended or appended to an entry in the bibliography. \revtex~4 required by-hand editing of the Bib\TeX\ output. See Section~\ref{sec:prepend} for an example of how to do this.  \end{itemize}  Proper formatting of references requires Patrick Daly's \classname{natbib} citation package. \BibTeX\ style files  for APS and AIP journals are created using his \classname{custom-bib} tool kit. From an author's point of view, all this means is that a proper  \revtex~4.1 installation requires having \classname{natbib} (version 8.31a  or higher) installed. It also means that the full set of  \classname{natbib} functionality is available from within \revtex~4.1  (but see the \textit{APS Author Guide for \revtex~4.1} and \textit{Author's Guide to AIP Substyles for \revtex~4.1} for restrictions if  submitting to an APS or AIP journal). The \classname{natbib} documentation contains many examples; see in  particular the \verb+natnotes.tex+ file for a convenient summary. Please also note that \classname{natbib 8.3} and later now gives an error (rather than merely a warning as in earlier versions) if you try to use a Bib\TeX\ file that isn't compatible with author-year style citations with a journal style that requires author-year citations (such as \textit{Reviews of Modern Physics}).  \subsection{Citing a reference}  As in standard \LaTeX, references are cited in text using the  \cmd\cite\marg{key} command and are listed in the bibliography using  the \cmd\bibitem\marg{key} command. The \cmd\cite{} macro enables  \revtex~4.1 to automatically number the references in the manuscript.  A typical example might be:  \begin{verbatim}  String theory\cite{GSW} attempts to   provide a theory of everything.  \end{verbatim}  The corresponding \cmd\bibitem{} would be:  \begin{verbatim}  \bibitem{GSW} M.~Greene, J.~Schwarz, and  E.~Witten, \textit{Superstring Theory:  Introduction}, (Cambridge University  Press, London, 1985).  \end{verbatim}  Journals differ in how the \cmd\cite\ will be displayed. Most APS journals  display the citation in-line, as a number, enclosed in square brackets,  \textit{e.g.}, ``String theory[1] attempts\dots.'' Other journals  (most notably \textit{Physical Review B})  instead use a number in a superscript: ``String theory$^{1}$ attempts\dots.''  Selecting the journal substyle using a class option (such as  \classoption{prb}) will invoke the appropriate style.  In journal substyles using superscripts,  the macro the \cmd\onlinecite\marg{key} is necessary to get the number  to appear on the baseline.  For example, ``String theory (see, for example,  \verb+Ref.~\onlinecite{GSW}+)'' will give the output  ``String theory (see, for example, Ref.~1).''  The \cmd{\onlinecite} command has the same semantics as  \classname{natbib}'s \cmd{\citealp} command.  A \cmd\cite\ command with multiple keys is formatted with consecutive  reference numbers collapsed; e.g., [1,2,3,5] will be output as  [1--3,5]. To split the list over more than one line, use  a \verb+%+ character immediately following a comma:  \begin{verbatim}  . . . \cite{a,b,c,d,e,f,%  g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}  \end{verbatim}  The \verb+%+ avoids unwanted spaces.  \subsection{Author/Year (Non-numeric) Citations}  \textit{Reviews of Modern Physics} uses a citation style based on the  first author's last name and the year of the reference rather than a  simple number. Support for this style of citing references is the  primary reason \revtex~4.1 uses the \classname{natbib}  package. \classname{natbib} uses an optional argument to the  \cmd\bibitem\ macro to specify what text to use for the \cmd\cite\  text:  \begin{quote}  \cmd\bibitem\verb+[+\meta{short-name}\verb+(+\meta{year}\verb+)+\meta{long-name}\verb+]+  \end{quote}  where \meta{short-name} is the author name used in a parenthetical citation,   \meta{long-name} that used in a textual citation, and   \meta{year} is the year. More concretely, the \cmd\bibitem\ example  above would appear as  \begin{verbatim}  \bibitem[Greene et al.(1985)Green,  Schwarz, and Witten]{GSW}  M.~Greene, J.~Schwarz, and E.~Witten,  \textit{Superstring Theory},  (Cambridge Press, London, 1985).  \end{verbatim}  When the citation constitutes part of the grammar of the sentence,  the \cmd\textcite\marg{key} command may be used (analogous to the  \cmd\onlinecite\ command above). Both \cmd\textcite\ and  \cmd\onlinecite\ are built upon \classname{natbib}'s rich repertoire of  macros (\cmd\citep{}, \cmd\citet{}, etc.). These macros are available in  \revtex~4.1; however, APS authors must follow the  \textit{APS Author Guide for \revtex~4.1}  guidelines regarding \classname{natbib}'s macros.  \subsection{Combined Author/Year and Numeric Citations}  AIP's \textit{Journal of Mathematical Physics} uses a combined author/year and numerical citation style. \revtex~4.1 supports this referencing style. Please see the \textit{Author's Guide to AIP Substyles for \revtex~4.1} for more information about this style.  \subsection{\label{sec:use-bib}Using Bib\TeX}  The \cmd\bibitem{} entries can be coded by hand as above, of course, but the  use of \BibTeX\ with the new style files provided with \revtex~4.1 makes  it particularly simple to generate marked-up references that can, for  instance, take advantage of packages like  \classname{hyperref} for linking. They also save the trouble of having  to specify formatting like the italics for the book title in the above  example. And, for those wishing to use author/year citations, \BibTeX\   will automatically generate the appropriate optional arguments for the  \cmd\bibitem\ commands.  \BibTeX\ is an adjunct to \LaTeX\ that aids in the  preparation of bibliographies. \BibTeX\ allows authors to build up a  database or collection of bibliography entries that may be used for many  manuscripts. A \BibTeX\ style file then specifies how to transform the  entries into a proper \cmd\bibitem{} for a particular journal. Here we  give a brief summary of how to get started with \BibTeX. More details can be  found in the LaTeX books listed in the references.  Selecting a journal style by using an appropriate class option will  automatically select the correct \BibTeX\ style file from those included in  \revtex~4.1. Four basic \BibTeX\ style files are included: \file{apsrev4-1.bst} (APS journals using a numeric citation style, \textit{i.e.}, all but RMP), \file{apsrmp4-1.bst} (author/year style citations for RMP),  \file{aipauth4-1.bst} (AIP journal using an author/year citation style), and \file{aipnum4-1.bst} (AIP journals using a numeric citation style). In addition, there are ``long" versions for each of these that add the titles of cited articles to the bibliography. The selection can be overridden by specifying an  alternative \file{.bst} file using the standard \LaTeXe  \cmd\bibliographystyle\ macro. This must appear in the preamble  before the \envb{document} line in \revtex~4.1 (this differs from  standard \LaTeX).  The \BibTeX\ database files will contain entries such as:  \begin{verbatim}  @Book{GSW,  author=``M. Greene, J. Schwarz,  E. Witten'',  title=``Superstring theory:  Introduction'',  publisher=``Cambridge University  Press'',  address=``London'',  year=``1985''  }  \end{verbatim}  There are entry formats for articles, technical reports, e-prints,  theses, books, proceedings, and articles that appear in books or  proceedings. The styles provided with  \revtex~4.1 also allows URL's and e-print identifiers to be specified  for any of the different entry types. There is also an additional  ``collaboration'' field that can be used in addition to ``author'.'  To actually create the bibliography in the manuscript, the  \cmd\bibliography\marg{bib files} macro is used.   Here \meta{bib files} is a comma-separated list of \BibTeX\ bibliography  database files, each with the \file{.bib} extension. The  \cmd\bibliography\ macro should be placed at the location where the  references are to appear (usually after the main body of the  paper). When the manuscript is processed with \LaTeX\ for the first  time, the keys corresponding for the \cmd\cite{} macros used in the  manuscript are written out to the \file{.aux} file. Then \BibTeX\ should  be run (if the manuscript is called \file{paper.tex}, the command would  be \verb+bibtex paper+. This will produce a \file{.bbl} file containing all  of the \cmd\bibitem{}'s for the manuscript. Subsequent runs of \LaTeXe\  will call this file in to resolve the references. \LaTeXe\ should be run  repeatedly until all references are resolved.  The \BibTeX-produced \cmd\bibitem{}'s created using the \revtex\ style files appear considerably more complex than the example given  above. This is because the style files add in \cmd\bibinfo{},  \cmd\bibnamefont{}, \cmd\eprint{}, and \cmd\url{} macros for  specifying additional formatting and tagging. The \cmd\bibinfo\ macro  is mostly a do-nothing macro that serves merely to tag the information with  the field information from the original entry in the \BibTeX\ database.  The \cmd\eprint\ and \cmd\url\ macros can be used to create the  appropriate hyperlinks in target formats such as PDF.  For more information on using \BibTeX\ with \LaTeX, see Sections~4.3.1  and~C.11.3 of the \LUG\cite{LaTeXman}, Section~13.2 of \cite{Compan},  or the online \BibTeX\ manual \file{btxdoc.tex} from   \url{http://www.ctan.org/tex-archive/biblio/bibtex/distribs/doc/}.  \subsubsection{\texttt{arXiv.org} support in Bib\TeX}  \revtex~4.1 has better support for citing e-prints from \texttt{arXiv.org} For instance, the \texttt{.bib} entry  \begin{verbatim}  @Unpublished{Ginsparg:1988ui,  author = "Ginsparg, Paul H.",  title = "{Applied Conformal Field Theory}",  year = "1988",  eprint = "hep-th/9108028",  archivePrefix = "arXiv",  SLACcitation = "%%CITATION=HEP-TH/9108028;%%"  }  \end{verbatim}  will include the arXiv.org e-print identifier as \texttt{arXiv:hep-th/9108028} and hyperlink it (if using \texttt{hyperref}). The newer format for arXiv identifiers with primary classificiations will produce output such as \texttt{arXiv:0905.1949 [hep-ph]}.  \subsection{\label{sec:multiple}Multiple references in a single bibliography entry}  One of the most frequently requested features since the release of \revtex~4 has been to allow more than one reference to appear in a single bibliography entry when using Bib\TeX. This can now be done in \revtex~4.1 by using a starred (*) argument to the \cmd\cite\ command. This requires the latest version of \texttt{natbib}, developed in conjunction with \revtex~4.1, and the new \texttt{bst} files that come with \revtex~4.1. To combine multiple references into a single \cmd\bibitem, precede the second, third, etc. citation keys in the \cmd\cite\ command with an asterisk (*). For example \verb+\cite{bethe, *feynman, *bohr}+ will combine the \cmd\bibitem\relax s with keys \texttt{bethe}, \texttt{feynman}, and \texttt{bohr} into a single entry in the bibliography separated by semicolons.  \subsection{\label{sec:prepend}Prepending and/or appending text to a citation}  The expanded syntax for the \cmd\cite\ command argument can also be used to specify text before and/or after a citation. For instance, a citation such as:  \begin{verbatim}  [19] A similar expression was derived in  A. V. Andreev, Phys. Rev. Lett. 99, 247204  (2007) in the context of carbon nanotube  p-n junctions. The only difference is that no  integration over ky is present there.  \end{verbatim}  may be created by the following \cmd\cite\ command:  \begin{verbatim}  \cite{*[{A similar expression was derived  in }] [{ in the context of carbon nanotube  p-n junctions. The only difference is that  no integration over ky is present  there.}] andreev2007}  \end{verbatim}  Please note the use of curly braces to enclose the text within the square brackets as well as the spaces next to the brackets.  \section{Figures and Artwork}\label{sec:figures}  \subsection{\texttt{figure} environment}  Figures may be included into a \revtex~4.1 manuscript by using the  standard \LaTeXe\ macros. It should be noted that \LaTeXe\ includes  several powerful packages for including the files in various  formats. The two main packages are \classname{graphics} and  \classname{graphicx}. Both offer a macro called  \cmd\includegraphics\oarg{args}\marg{filename};   they mainly differ in how arguments for  controlling figure scaling, translation, and orientation  are specified. For more information on the enhancements of the \classname{graphicx} package,   see \cite{CompanG} or the guide \file{grfguide.pdf} available at  \url{http://www.ctan.org/tex-archive/macros/latex/required/graphics/}.  \revtex~4.1 no longer has the \classoption{epsf} class option, though  the \classname{epsfig} package provides a similar interface.  The \env{figure} environment should be used to add a caption to the figure and  to allow \LaTeX\ to number and place the figures where they fit best.   \LaTeX\ will label and automatically number the captions FIG.~1,  FIG.~2, etc. For example:  \begin{verbatim}  \begin{figure}  \includegraphics{fig1.eps}  \caption{\label{fig1}Text of first caption.}  \end{figure}  \end{verbatim}  Note how the \cmd\label\marg{key} command is used to cross-reference  figures in text. The \cmd\label\marg{key} command should be inserted  inside the figure caption. As usual, the \cmd\ref\marg{key} macro can  then by used to refer to the label: ``As depicted in  FIG.\verb+~\ref{fig1}+\dots''.  Figures are normally set to the width of the column in  which they are placed. This means that in two-column mode, the figure  will be placed in a single, narrow column. For wide figures, the  \cmd\figure\verb+*+ environment should be used  instead. This will place the figure across both columns (the figure  usually will  appear either at the top or the bottom of the following page).  Captions less than one line long are centered under the figure,  otherwise they span the width of the figure.  Note that is unnecessary (and undesirable) to use explicit centering  commands inside the float environments.  \subsection{\texttt{video} environment}  Papers often refer to multimedia material such as videos. The \texttt{video} environment is identical to the \texttt{figure} environment, but the caption will be labeled as a \textbf{Video} (with its own counter independent of figures). A URL can also be specified so that the caption label can be linked to the online video (if using the \texttt{hyperref} package). The included graphic (using \cmd\includegraphics\ from the \texttt{graphics} or \texttt{graphicx} package) would be a representation frame from the video. A \texttt{\cmd\listofvideos} is also provided. For example:  \begin{verbatim}  \begin{video}  \includegraphics{videoframe.jpg}  \setfloatlink{http://some.video.com/fun.mov}  \caption{\label{vid:interest}This is a video  of something fun.}  \end{video}  \end{verbatim}  There is also a corresponding \cmd\listofvideos\ command.  \section{Tables}\label{sec:tables}  Tables are very similar to figures. They should be input using the  \env{table} environment as detailed below, and   \LaTeX\ will label and number the captions TABLE~1, TABLE~2, etc.  (or in whatever format required by the chosen journal  substyle). Tables without captions won't be numbered.  Each table must begin with \envb{table}, end with \enve{table}. A  caption can be specified using the \cmd\caption\marg{text} command.  Captions less than one line long are centered under the figure,  otherwise they span the width of the figure.  To refer to the table via cross-referencing, a \cmd\label\marg{key}  command should appear within the \cmd{\caption}. Use the  \cmd\ref\marg{key} command to cite tables in text. The \env{table}  environment will set the table to the width of the column. Thus, in  two-column mode, the table will be confined to a single column. To set a  table to the full width of the page, rather than the column, use the  \env{table*} environment.  The heart of the table is the  \env{tabular} environment. This will behave for the most part as in  standard \LaTeXe\ (please refer to Section~3.6.3 and Appendix~C.10.2 of the  \LUG{} for more details about the \env{tabular} environment).  Note that \revtex~4.1 no longer automatically adds double (Scotch) rules  around tables. Nor does the \env{tabular} environment set various  table parameters for column spacing as before. Instead, a new  environment \env{ruledtabular} provides this functionality. This  environment should surround the \env{tabular} environment:  \begin{verbatim}  \begin{table}  \caption{\label{}....}  \begin{ruledtabular}  \begin{tabular}  ...  \end{tabular}  \end{ruledtabular}  \end{table}  \end{verbatim}  A basic table looks as follows:  \begin{verbatim}  \begin{table}  \caption{\label{tab:example}Text of table caption.}  \begin{ruledtabular}  \begin{tabular}{ll}  Heading 1 & Heading 2\\  Cell 1 & Cell 2\\  \end{tabular}  \end{ruledtabular}  \end{table}  \end{verbatim}  The \env{quasitable} environment is no longer in \revtex~4.1. The  standard \env{tabular} environment can be used instead because it  no longer puts in the double rules.  \subsection{Aligning on a decimal point}  Numerical columns should align on the decimal point (or  decimal points if more than one is is present). This is accomplished  by again using a standard \LaTeXe\ package, \classname{dcolumn} which  must be loaded in the manuscript's preamble:  \begin{verbatim}  \usepackage{dcolumn}  \end{verbatim}  Once this package is loaded, the column specifier `\texttt{d}' can be  used in the table's \env{tabular}\marg{preamble} enviroment preamble.  The `\texttt{d}' should be used for simple numeric data with a single  decimal point.  %  The entry of a \texttt{d} column is typeset in math mode; do not  insert any \verb+$+ math delimiters into a `\texttt{d}' column. Items  without a decimal point are simply set in math mode, centered. If  text is required in the column, use \cmd\text\ or \cmd\mbox\ as  appropriate. If multiple decimal points are present then the last is  used for alignment. To escape from the `\texttt{d}' column use  \cmd\multicolumn\ as usual. See the sample file \file{apssamp.tex} for examples.  \subsection{Footnotes in Tables}\label{sec:tablenote}  Footnotes in a table are labeled \emph{a}, \emph{b}, \emph{c},  etc. They can be specified by using the \LaTeX\ \cmd\footnote\  command. Furthermore,  \cmd\footnotemark\ and \cmd\footnotetext\ can be used so that multiple entries  can to refer to the same footnote. The footnotes for a table are typeset  at the bottom of the table, rather than at the bottom of the page or  at the end of the references. The arguments for \cmd\footnotemark\ and  \cmd\footnotetext\ should be numbers 1, 2, \dots. The journal style  will convert these to letters. See sample file \file{apssamp.tex} for  examples and explanations of use.  \subsection{Dealing with Long Tables}  By default, tables are set in a smaller size than the text body  (\cmd\small). The \cmd\squeezetable\ declaration makes the table font  smaller still (\cmd\scriptsize). Thus, putting the  \cmd\squeezetable\ command before the \envb{table} line in a table  will reduce the font size. If this isn't sufficient to fit  the table on a page, the standard \LaTeXe\ \classname{longtable}  package may be used. The scope of the  \cmd\squeezetable\ command must be limited by enclosing it with a group:  \begin{verbatim}  \begingroup  \squeezetable  \begin{table}  [...]  \end{table}  \endgroup  \end{verbatim}  Tables are normally set to the width of the column in  which they are placed. This means that in two-column mode, the table  will be placed in a single, narrow column. For wide tables, the  \cmd\table\verb+*+ environment should be used  instead. This will place the table across both columns (the table  usually will  appear either at the top or the bottom of the following page).  To break tables across pages, \revtex~4.1requires adding to the  table a float placement option of [H] (meaning put the table ``here''  and effectively ``unfloating'' the table) to the \envb{table}  command. The commands \verb+\\*+ and \cmd{\samepage} can be used to  control where the page breaks occur (these are the same as for the  \env{eqnarray} environment).  Long tables are more robustly handled by using the  \classname{longtable.sty} package included with the standard \LaTeXe\  distribution (put \verb+\usepackage{longtable}+ in the preamble). This  package gives precise control over the layout of the table.  The \revtex~4.1 package contains patches that enable the  \classname{longtable} package to work in two-column mode. Of course, a  table set in two-column mode needs to be narrow enough to fit within  the column. Otherwise, the columns may overlap. \revtex~4.1 provides  an additional environment \env{longtable*} which allows a longtable to  span the whole page width. Currently, the \env{longtable*} and  \env{ruledtabular} environments are incompatible. In order to get the  double (Scotch) rule, it is necessary to add the \verb+\hline\hline+  manually (or define \verb+\endfirsthead+ and \verb+\endlastfoot+  appropriately). For more documentation on the \env{longtable}  environment and on the package options of the  \classname{longtable} package, please see the documentation available at  \url{http://www.ctan.org/macros/latex/required/tools/longtable.dtx} or  refer to \cite{Compan}.  \section{Placement of Figures, Tables, and Other Floats}  \label{sec:place}  By default, figures and tables (and any other ``floating'' environments  defined by other packages) float to the top or bottom of the page  using the standard \LaTeX\ float placement mechanism. Initially, each  \env{figure} or \env{table} environment should be put immediately  following its first reference in the text; this will usually result in  satisfactory placement on the page. An optional argument for either   environment adjusts the float placement. For example:  \begin{quote}  \envb{figure}\oarg{placement}\\  \dots\\  \enve{figure}  \end{quote}  where \meta{placement} can be any combination of \verb|htbp!|, signifying  ``here'', ``top'', ``bottom'', ``page'', and ``as soon as possible'',  respectively. The same placement argument may be added to a  \envb{table}. For more details about float placement,   see the instructions in the \LUG, Appendix~C.9.1.  In two-column mode, a page may contain both a \env{widetext}  environment and a float. \revtex~4.1 may not always be able to  automatically put the float in the optimal place. For instance, a  float may be placed at the bottom of a column just before the  \env{widetext} begins. To workaround this, try moving the float  environment below the \env{widetext} environment. Alternative  \meta{placements} may also alleviate the problem.  \env{figure} and \env{table} environments should not   be enclosed in a \env{widetext} environment to make them span  the page to accommodate wide figures or tables. Rather, the  \env{figure*} or \env{table*} environments should be used instead.  Sometimes in \LaTeX\ the float placement mechanism breaks down and a  float can't be placed. Such a ``stuck'' float may mean that it and all  floats that follow are moved to the end of the job (and if there are  too many of floats, the fatal error \texttt{Too many unprocessed floats}  will occur). \revtex~4.1 provides the class option  \classoption{floatfix} which attempts to invoke emergency float  processing to avoid creating a ``stuck'' float. \revtex~4.1 will provide  a message suggesting the use of  \classoption{floatfix}. If \classoption{floatfix} doesn't work or if  the resulting positioning of the float is poor, the float should be  repositioned by hand.  \revtex~4.1 offers an additional possibility for placing the floats. By  using the either the \classoption{endfloats} or the  \classoption{endfloats*} class option all floats may be held  back (using an external file) and then set elsewhere in the document  using the the commands \cmd\printtables\ and \cmd\printfigures{},  placed where the tables and figures are to be printed (usually at the  end of the document). (This is similar to the standard  \cmd\printindex\ command). Using a \texttt{*}-form of the commands  (\cmd\printfigures\verb+*+ and  \cmd\printtables\verb+*+) will begin the figures  or tables on a new page. Alternatively, the option  \classoption{endfloats*} may be used to change the behavior of the  non-\texttt{*}-forms so that every float will appear on a separate  page at the end.  Without one of the \classoption{endfloats} class options, these float  placement commands are silently ignored, so it is always safe to use  them. If one of the \classoption{endfloats} class options is given,  but the \cmd\printtables\ command is missing, the tables will be  printed at the end of the document. Likewise, if \cmd\printfigures\ is  missing, the figures will be printed at the end of the document.  Therefore it is also safe to omit these commands as long as \revtex's  default choices for ordering figures and tables are satisfactory.  The \classoption{endfloats} option (or perhaps some journal substyle  that invokes it), requires explicit \envb{figure}, \enve{figure},  \envb{table}, and \enve{table} lines. In particular, do \emph{not}  define typing shortcuts for table and figure environments, such as  \begin{verbatim}  \def\bt{\begin{table}}% Incompatible!  \def\et{\end{table}}%  \end{verbatim}  Please note that it is generally undesirable to have all floats moved  to the end of the manuscript. APS no longer requires this for  submissions. In fact, the editors and referees will have an easier time  reading the paper if the floats are set in their normal positions.  \section{Rotating Floats}  Often a figure or table is too wide to be typeset in the standard  orientation and it is necessary to rotate the float 90  degrees. \revtex~4.1 provides a new environment \env{turnpage} as an  easy means to accomplish this. The \env{turnpage} environment depends  on one of the packages \classname{graphics} or \classname{graphicx}  being loaded. To use the \env{turnpage} environment, simply enclose  the \env{figure} or \env{table} environment with the \env{turnpage}  environment:  \begin{verbatim}  \documentclass[...]{revtex4}  \usepackage{graphicx}  [...]  \begin{turnpage}  \begin{figure} or \begin{table}  [...]  \end{figure} or \end{table}  \end{turnpage}  \end{verbatim}  A turnpage float will be typeset on a page by itself. Currently, there  is no mechanism for breaking such a float across multiple pages.  \section{\revtex~4.1 symbols and the \classname{revsymb4-1} package}  Symbols made available in earlier versions of \revtex\ are  defined in a separate package, \classname{revsymb4-1},  so that they may be used with other classes.  This might be useful if, say, copying text from a \revtex\ document to  a non-\revtex\ document. \revtex~4.1 automatically includes these  symbols so it is not necessary to explicitly call them in with a   \cmd\usepackage\ statement.  Table~\ref{tab:revsymb} summarizes the symbols defined in this package.  Note that \cmd{\overcirc}, \cmd{\overdots}, and \cmd{\corresponds} are  no longer in \revtex~4.1. Use \cmd{\mathring} (standard in \LaTeXe),  \cmd{\dddot} (with the \classoption{amsmath} package loaded), and   \cmd\triangleq\ (with the \classoption{amssymb} class option) respectively.  \cmd{\succsim}, \cmd{\precsim}, \cmd{\lesssim}, and \cmd{\gtrsim} are  also defined either in \classname{amsmath} or \classname{amssymb}. The  AMS versions of these commands will be used if the appropriate AMS  package is loaded.  \begin{table}  \caption{\label{tab:revsymb}Special \revtex~4.1 symbols, accents, and  boldfaced parentheses defined in \file{revsymb.sty}}  \begin{ruledtabular}  \begin{tabular}{ll|ll}  \cmd\lambdabar & $\lambdabar$ &\cmd\openone & $\openone$\\  \cmd\altsuccsim & $\altsuccsim$ & \cmd\altprecsim & $\altprecsim$ \\  \cmd\alt & $\alt$ & \cmd\agt & $\agt$ \\  \cmd\tensor\ x & $\tensor x$ & \cmd\overstar\ x & $\overstar x$ \\  \cmd\loarrow\ x & $\loarrow x$ & \cmd\roarrow\ x & $\roarrow x$ \\  \cmd\biglb\ ( \cmd\bigrb ) & $\biglb( \bigrb)$ &  \cmd\Biglb\ ( \cmd\Bigrb )& $\Biglb( \Bigrb)$ \\  & & \\  \cmd\bigglb\ ( \cmd\biggrb ) & $\bigglb( \biggrb)$ &  \cmd\Bigglb\ ( \cmd\Biggrb\ ) & $\Bigglb( \Biggrb)$ \\  \end{tabular}  \end{ruledtabular}  \end{table}  \section{Other \revtex~4.1 Features}  %\subsection{Hooks}  %To be written....  \subsection{Job-specific Override Files}  \revtex~4.1 allows manuscript-specific macro definitions to be put  in a file separate from the main \TeX\ file. One merely creates a file  with the same basename as the \TeX\ file, but with the extension  `.rty'. Thus, if the \TeX\ file is names man.tex, the macro  definitions would go in man.rty. Note that the .rty file should be in  the same directory as the \TeX\ file. APS authors should follow the  guidelines in the \textit{APS Author Guide for \revtex~4.1} when  submitting. Similarly, AIP authors should refer to the \textit{Author's Guide to AIP Substyles for \revtex~4.1}  \begin{thebibliography}{}\label{sec:TeXbooks}  \bibitem[Knuth(1986)]{TeXbook} D.E. Knuth, \emph{The \TeX book},  (Addison-Wesley, Reading, MA, 1986).  \bibitem[Lamport(1996)]{LaTeXman} L. Lamport, \emph{\LaTeX, a Document  Preparation System}, (Addison-Wesley, Reading, MA, 1996).  \bibitem[Kopka(1995)]{Guide} H. Kopka and P. Daly, \emph{A Guide to  \LaTeXe}, (Addison-Wesley, Reading, MA, 1995).  \bibitem[Goossens(1994)]{Compan} M. Goossens, F. Mittelbach, and  A. Samarin, \emph{The \LaTeX\  Companion}, (Addison-Wesley, Reading, MA, 1994).  \bibitem[Goossens(1997)]{CompanG} M. Goossens, S. Rahtz, and  F. Mittelbach, \emph{The  \LaTeX\ Graphics Companion}, (Addison-Wesley, Reading, MA, 1997).  \bibitem[Rahtz(1999)]{CompanW} S. Rahtz, M. Goossens, \emph{et  al.},\emph{The \LaTeX\ Web Companion}, (Addison-Wesley, Reading, MA, 1999).  \end{thebibliography}  \end{document}