[Pw_forum] rho mixing problem with PAW

[Paolo Giannozzi]

On Oct 9, 2012, at 14:31 , Giuseppe Mattioli wrote:

>       Error in routine mix_rho (1):
>       negative dr2

this is something that occasionally happens with PAW, for unclear
reasons. "dr2" is a quantity that should always be positive, but with
PAW sometimes it isn't. Try this: in PW/src/scf_mod.f90, replace line  
600
   IF (okpaw)         rho_ddot = rho_ddot + paw_ddot(rho1%bec, rho2%bec)
with
   IF (okpaw)         rho_ddot = rho_ddot + ABS ( paw_ddot(rho1%bec,  
rho2%bec) )
No warranty ...

P.

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Paolo Giannozzi, Dept of Chemistry&Physics&Environment,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222