[Pw_forum] help for convergence in "Computing Second order response"

[Paolo Giannozzi]

On Oct 26, 2007, at 7:14 , hyello25 Qgrui wrote:

>  When I do raman calculation of Li2O, I found the "second order  
> response"
> process is not convergent.

try to reduce the alpha_mix parameter

>  What is more wried, this situation never happened days before when
> using the exactly same input file and PPs. That is , I cannot  
> repeat the
> result again with all the same input file though I check all the  
> input file
> carefully. The scf result are the same, but the ph.x gave different
> convergence process. Besides, I got different raman frequencies.

you are not doing the same calculation. Computers are deterministic,
even if it often happens that they look like random number generators

Paolo
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Paolo Giannozzi, Dept of Physics, University of Udine
via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222