[Pw_forum] convergence problems in phonon calculations

Thomas Gruber thomas.gruber at physik.tu-freiberg.de
Fri Feb 17 18:25:42 CET 2012

Dear all,

I am doing some phonon calculations and have some convergence problems 
in the "Self-consistent Calculation" at some q-points and 
Representations. I noticed that the "|ddv_scf|^2"-value jumps in the 
second step to a greater value, like in the scf calculation I have done 
for this phonon calculation. I minimized the jump in the scf 
calculation, when I use "mixing_mode='TF' ". Is this option also 
implemented for ph.x?
I also tried decreasing the "alpha_mix"-value, it helps but I hope to 
get better results with mixing_mode (as it does in an scf test 
calculation). Do I have other options to decrease the cpu time and 
number of iterations? (a normal convergence takes 10 iterations and not 
30 with alpha_mix 0.3)
Thanks for help

Thomas Gruber
Institute for Theoretical Physics
TU Bergakademie Freiberg

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