[Pw_forum] total force ascend in the course of VC-relax

[Q.J.Wang]

Dear all
    I did geometry optimization with vc-relax in a supercell. When I increase the concentration of doped atoms ,the value of total force ascend instead of declining.Before I did not increase the concentration of doped atoms ,It converges well .Anyone who encounter the same problem as me ?
    The second problem is when I increase the relative distance of the two doped atoms in the supercell and did geometry optimization with vc-relax,and the error turn up as like : from c_bands : error #         1
                        too many bands are not converged
So I am puzzled why before I increase relative position of two doped atoms the vc-relax converged and the latter turns up error in the same parameter .
Any advice will be appreciated .
--

Best regards
 
Q.J.Wang
 
XiangTan University 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.democritos.it/pipermail/pw_forum/attachments/20091015/3423199a/attachment.htm