[Pw_forum] phonon calculation

[yumin qian]

     I did a phonon calculation with the  A-spin type CaCrO3 system , the
system is Pbnm structure , in the unit cell there are 20 atoms and the  Cr
atoms are spin parallel in a-b plane and anti-parallel along c axis .
After a scf calculation by pw.x whit a k-point mesh of 6×6×4  I choose a q
point mesh of 4×4×4 but the  thresh cann't be reached and  ddv_scf|^2
dangling around 1.0E-7  ,I use the alpha_mix =  0.700 , how to make it
converge for such large system?

-- 
Sincerely Y. M. Qian
Lab.of Condensed Matter Theory and Materials Computation
Institute of Physics
Chinese Academy of Sciences
Tel:  + 8610 8264 9147
E-Mail:yuminqian at gmail.com <E-Mail%3Ayuminqian at gmail.com>
P.O.Box 603   Beijing 100190
China
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