esta.phonon.atm_displacements_selective_general_disp
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gen_disp(posfile, qe_part_file, val_displacement)
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generate set of displacement of atoms in +ve and - directions by val_displacement (e.g. earlier it was delta_x = 0.04 Ang; this parameter may be varied according to need and physical requirements )
input: poscar file; string output: set of files named: positions_01_0 and like that fist integer is atom index; → 0, 1, 2 ... N-1 (N=no of atoms) second intege is positon index; i.e. x , y, and z → 0,1,2 last integer is for -ve and +disp → 0,1 [0/1] at the end means displacement along +ve and -ve directions respectively
NOTE: both atomic position outputs: qe and poscar are implemented NOTE: Generally val_displacement should be 0.04 ang for bulk materials for surface or surface species involved during chemical reactions, it to be 0.02 angstrom.
.. note:: displacement for atoms to find the hessian matrix should be 0.0075 Ang (see Accessing Numerical Energy Hessians with Graph Neural Network Potentials and Their Application in Heterogeneous Catalysis): For each direction, two displacements of 0.0075 ˚A were performed. The electronic convergence criterion was met if the change in energy between iterations was less than 1 × 10−6 eV .
: Sept, 2019
email: sonukumar.physics@gmail.com