[Phonopy-users] thermal conductivity difference in with and without symmetrized IFCs

[MUKESH S. <gkp...@gm...>]

Dear Phonopy users and Prof. Togo,

While performing thermal conductivity calculation with phono3py, we find
that there are quite differences in thermal conductivities values computed
with not-symmetrized and symmetrized IFCs (2nd order and 3rd order both).

For symmetrized IFCs, we have used:
phono3py --sym-fc
phono3py --fc3 --fc2 --dim="3 3 1" --dim_fc2="5 5 1" --mesh="19 19 1"  -c
POSCAR_unit --nac --br

For not-symmetrized IFCs, we have used:
phono3py  --dim="3 3 1" --dim_fc2="5 5 1" --mesh="19 19 1"  -c POSCAR_unit
--nac --br

So our questions are:

1- Could you please suggest which methods we should use? And why?

2- What are the reasons for the difference between computed values of
thermal conductivity with and without symmetrization of force constants?


Your suggestions and references would be appreciable.



Thanks and regards
Mukesh Singh
Research Scholar
Department of Physics,
IIT BOMBAY(400076)