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Edwin E. Quashie edited section_Introduction_The_interaction_of__.tex
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The interaction of charged particles with matter has been a subject of extensive research over many decades; it findings provide precise information for many technological applications such as nuclear safety, applied material science, medical physics and fusion and fission applications \cite{Komarov_2013,Patel_2003,Caporaso_2009,Odette_2005}.
When a fast ion moves through a solid, it loses kinetic energy due to the excitations of the target electrons and the path of their trajectory.
This energy-loss phenomenon plays an important role in many experimental studies involving radiation in solids, surfaces and nanostructures
[add citation]. \cite{Chenakin_2006,Figueroa_2007,Markin_2008,Kaminsky_1965,Lehmann_1978,Sigmund_2014,Nastasi_1996}.
The complexity of describing the dynamic interaction between charged particles and solids has initiated a large amount of research both experimentally and theoretically in recent years; in the latter the condensed matter community, however, have initiated sophisticated computer simulation techniques with considerable success.
Among the many measurable quantity the stopping power $\mathrm(S)$ \cite{Ferrell_1977} has received much attention; it provided detailed information regarding the energy transfer between the incoming projectile and the solid target.
Varies models and theories have been proposed to calculate stopping cross sections ($\mathrm{SCS}$); even today a unified theoretical approach suitable for different projectiles and energies is not available in the literature. Employing the First Born Approximation (FBA), Bethe \cite{Bethe_1930_EN} has reported the calculation of inelastic and ionization cross section. The Bloch correction \cite{Bloch_1933} provides a convenient link between the Bohr and the Bethe scheme. Fermi and Teller \cite{Fermi_1947} using electron gas models had reported electronic stopping for various targets. The Bethe formula for stopping has been studied in details by Lindhard and Winther \cite{Lindhard_Winther} on the basis of the generalized linear-response theory.
%models employed to study stopping of elementary charged particles in solids \cite{Bloch_1933,Bethe_1930} has stimulated this kind of study.
All these models require ad-hoc assumptions for studying stopping processes.
For A recent review \cite{Race_2010} has full detail of theoretical developments for calculating electronic stopping in
metals there are a few reviews \{\cite{Race_2010} and see the Ref. therin\} show theoretical progress metals. %Ab-initio electronic stopping calculations suffer convergence issues and
we not repeating them here. fail to reproduce experimental findings.
The development of time dependent density functional theory (TDDFT) \cite{Runge_1984} enhanced the diverse study of many body
problems. problems involving the slowing down of charged projectiles in metals. It has enjoyed much consideration owing to its electron dynamics both self-consistency and non-perturbative way \cite{Kohn_1965}.
In studying the role of radiation damage in $\mathrm{H^+ + Al}$ interactions Correa {\emph et al} \cite{Correa_2012} have shown that the electronic excitations due to molecular dynamics (MD) are quite different from the adiabatic outcome. Even today the inclusion of non adiabatic effects in a real calculation poses a challenging problem. Recently Schleife {\emph et al} \cite{Schleife_2015} have calculated the electronic stopping $\mathrm(S_\text{e})$ by $\mathrm{H}$ and $\mathrm{He}$ including non-adiabatic interactions and found that off-channeling trajectories along with the inclusion of semicore electrons enhance the $\mathrm(S_\text{e})$ resulting better agreement with the experiment.
In studying the role of radiation damage in ion-solid interactions Correa {\emph et al} \cite{Correa_2012} have shown that the electronic excitations due to molecular dynamics (MD) are quite different from the adiabatic outcome. The inclusion of non adiabatic effects in real calculations remains a challenging problem even today. Using the first principles descriptions Schleife {\emph et al} \cite{Schleife_2015} have calculated the electronic stopping by $\mathrm{H}$ and $\mathrm{He}$ projectile including non-adiabatic interactions.
It was observed that the role of both off-channeling trajectories and consideration of semicore electrons enhances the stopping power and yields better agreement with the experimental results.
Using a quantal method based on TDDFT, Quijada {\emph et. al.} \cite{Quijada_2007} have studied the energy loss of protons and anti-protons moving inside metalic Al and obtained good results for the projectile-target energy transfer over a wider energy range.
Recently Uddin {\emph et al.} \cite{Alfaz_Uddin_2013} have calculated stopping cross sections for various media with atomic number $Z=2$ to $100$ using realistic electron density with four fitted parameters and obtained
$\sim 15\%$ close agreement
($\sim 15\%$) with the \textsc{Srim}
data \cite{Ziegler_2010}. data. Using a single formula with
fewer less parameters Haque {\emph et al.} \cite{Haque_2015} have reported proton impact $\mathrm{SCS}$ with encouraging results.
The recent measurement \cite{Cantero_2009} by slow $\mathrm{H^+}$ in $\mathrm{Cu}$ reveals In the low energy region the
stopping energy loss in metal is due to
conduction band electronic the excitation
at lower velocities. The combined effects of
both the free a portion of electrons
and around the
loosely bound $d$ electrons causes Fermi level to empty states in the conducting band. But at higher energies, a
change minimum momentum transfer of the
slope. This study supports projectile is possible due to its short duration close to the target. In this
even upto $v = 0.01 ~\mathrm{a.u.}$ (see Figure \ref{fig:log_stopping_power}). The experimental results of Nomura and Kiyono \cite{Nomura_1975} on $\mathrm{H^+ + Cu}$ film show region the
dependence of $\mathrm(S_\text{e})$ on incident velocity agrees with electronic curve has a maximum due to the
calculation limited response time of
Lindhard {\emph et al} \cite{Lindhard_Scharff_Schiott}. target electrons to the projectile ions.
In %In recent years, the
low energy region the energy loss in metal is due to the excitation of a portion development of
electrons around time-dependent methods have enhanced the
Fermi level to empty states in the conducting band. But at higher energies, a minimum momentum transfer diverse study of
many body problems involving the
projectile is possible due to its short duration close to the target. In this region the electronic curve has a maximum due to the limited response time slowing down of
target electrons charged projectiles both in solids and gases. The time dependent density functional theory (TDDFT) on the other hand has enjoyed much consideration owing to
the projectile ions. its electron dynamics both self-consistency and non-perturbative way.
We report here an application of the TDDFT that embodies a plane-wave basis set that represents accurately the electron dynamics \cite{Correa_2012,Schleife_2012,Schleife_2014} for proton impact collision of $\mathrm{Cu}$ crystal. The suitability of this method is tested by evaluating the
electronic stopping $\mathrm(S_\text{e})$.
Our results are compared with those of \textsc{Srim} as well as available experimental values.%
%
%Using a quantal method based on TDDFT, Quijada {\emph et. al.} \cite{Quijada_2007} have studied the energy loss of protons and anti-protons moving inside metalic Al and obtained good results for the projectile-target energy transfer over a wider energy range.
%In recent years, the development of time-dependent methods have enhanced the diverse study of many body problems involving the slowing down of charged projectiles both in solids and gases. The time dependent density functional theory (TDDFT) on the other hand has enjoyed much consideration owing to its electron dynamics both self-consistency and non-perturbative way.