Solution LAB1 ecutwfc convergence 2

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Convergence of total energy differences wrt the kinetic energy cutoff

Use the same machinery (script to run the calculations, scripts to extract data from the output file) developed for the previous exercise, Solution to Exercise 3.

There we have been running calculations for alat=6.741. Let's pick a lattice variation, say 2%. Change the script to run with such a modified parameter. For instance:

 #
 # set vars
 #
 stretch=0.01
 alat0=6.741
 alat=`echo $alat0 $stretch | awk '{ print $1*(1.0+$2)}'`
 nk=8

(of course it is also possible to just change the hardcoded alat value in the script).

It is also important to change the input and output filenames, e.g. modifying label:

 #
 label="nk${nk}_stretch${stretch}_ecut${ecutwfc}" 

We are now in the position to run the calculations for the new system for a range of ecutwfc values.