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This is step-by-step example how to calculate phonon dispertion with CASTEP.
1. Generate supercell based on structrural parameters given in unitcell.cell
file by running:
% phonopy -d --dim="2 2 2" --castep -c unitcell.cell
In this example file unitcell.cell contains initial spin values in positions_frac BLOCK.
As well as the value of the U parameter in LDA+U approximation.
2. Use make_displ_dirs.sh bash script to make directories with input files needed to
calculate FORCES for supercells.
% make_displ_dirs.sh supercell.param tail.cell
Please note file supercell.param is the standart CASTEP file with paremeters (convergence
criteria, Ecut, functional name etc.). The file with name tail.cell contains k-mesh
description, U parameter value, symmetry operation E, and name of pseudopotential.
3. Run CASTEP calculation in displ-001 directory
4. Generate FORCE_SETS file by running:
% phonopy --castep -f displ-001/supercell.castep displ-002/supercell.castep
5. Finally plot phonon bandstructure by running the following command:
% phonopy --castep -c unitcell.cell -p band.conf
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