[Pw_forum] convergence problem for charged simulation cell

[Alexey Akimov]

Dear all,

I'm trying to calculate md of a system with the positive charge (+1) of the simulation cell. However it seems like a hard task,
because even the first step is not converging (electronic iteration). I used setup to allow up to 100 electronic iterations, but
this is not enough to achieve the convergence. I also tried to decrease the mixing parameter to 0.4, as was suggested in some of the
previous posts. I tried to increase charge density cutoff to 10*ecutwfc.

Also the program warns me that:
     (first iteration)
     WARNING: integrated charge=  2046.60000000, expected=  2047.00000000

     (10-th iteration)
     WARNING: integrated charge=  2046.01617514, expected=  2047.00000000

I do not know why program expects the charge corresponding to neutral system, while i ask for the positively charged one (tot_charge = 1.0)
I'm using version PWSCF v.4.3.2  with 4 processors. By the way, for neutral system the convergence does not give any problem.

Is there any ideas how to achieve the convergence for the charged simulation cell? Also i'm curious about those warning messages - can they be disregarded or it is me, who is missing something? May it be some bug of PWScf?

Thank you,
Alexey

-- 
Dr. Alexey V. Akimov

Postdoctoral Research Associate
Department of Chemistry
University of Rochester

aakimov at z.rochester.edu