quantum-espresso/PHonon/FD/example/README

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Illustrates the calulations needed to generate the interatomic force constants file
by using the finite displacements method
1) make a self-consistent calculation
cd $espresso_dir/PHonon/FD/example/inputfiles
$espresso_dir/bin/pw.x < si.scf.in > si.scf.out
2) create finite displacements in a supercell
$espresso_dir/bin/fd.x < fd.in > fd.out
3) run all the finite displacements and extract the forces
sh ../../run_fd
4) generate the file "si_ifc.fc" of the interatomic force constants
$espresso_dir/bin/fd_ifc.x < fd_ifc.in
cat ./fd_files/header.txt > si_ifc.fc
echo "F" >> si_ifc.fc
cat ./silicon_ifc.fc >> si_ifc.fc