deletions | additions       diff --git a/Introduction.tex b/Introduction.tex  index 3279663..f5e013c 100644  --- a/Introduction.tex  +++ b/Introduction.tex 
...
The flexibility of the real space grids makes them an ideal framework to develop and test new ideas.  Of course, not only an implementation   While in some cases it is possible to write code from scratch, in many cases it is necessary to perform complex operations that are not simple to implement. In those occasions developers  The Octopus code~\cite{Marques_2003,Castro_2006} is a software package developed collaboratively among researches from several groups around the world. Originally the code was focused on performing real-time TDDFT calculations~\cite{Yabana_1996}, however, it has evolved into a full package for electronic structure calculations.