[Pw_forum] electron phonon coupling of supercells

Eyvaz Isaev eyvaz_isaev at yahoo.com
Sun Oct 15 19:03:40 CEST 2006


 Hi, 

    Maybe I have not illustrate problem clearly. 

I want to perform EPC calculation on a supercell.

 Take NaCl as a example,


The example looks meaningless, NaCl is an insulator. You can try an  Al  supercell based on primitive unit cell..




 I construct a 2*2*2 supercell in the unit of primitive cell, whose space group is P1

 with the lowest symmetry. We all know that the EPC

 is a much time consuming process. Introducing symmetry 

operation to the system can speed the calculation greatly. 

My question is how can I introduce symmetry to the supercell I mentioned above in the precondition of obtaining physical results.


 

If I understood correctly, you would like to know the space group of  your  2x2x2 supercell and then use it in EPC calculations.   There are several ways to do it. Say, VASP, CRYSTAL03 (but not sure about LMTO47, because it requires only irreducible atomic positions and space group number, too).   ISOTROPY code seems to be very useful for this purpose: http://stokes.byu.edu/isotropy.html

Hope it helps.
Bests,
Eyvaz.





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