[Pw_forum] problem with vc-relax

[Olga Sedelnikova]

 Dear Sanjeev,


The problem is not with wrong charge. The error "charge is wrong" appeared
only for current options (smearing='mv', dynamics='damp', cg
diagonalization). If I use other physically appropriate options I will
obtain other errors: problem with davidson diagonalization, too small
trust_radius for bfgs method and sometimes error from efirmig.f90 "internal
error, cannot braket Ef". I have checked the dynamics of unit cell during
vc-relaxation by XCrySDen and found that interlayer distance and bond length
in graphite decreased  to ~ 2 and 1.2   Angstroms correspondingly. For
graphene calculations the unit cell was compressed along the z-axis and C-C
bond length decreased. However the "relax" calculation is fine.

Can anybody recommend the right options for "vc-relax" calculation of
graphite?

Thank you,

Olga Sedelnikova
Nikolaev Institute of Inorganic Chemistry of SB RAS



> Please visit this achieve
> http://www.democritos.it/pipermail/pw_forum/2006-August/004713.html, and
> http://www.democritos.it/pipermail/pw_forum/2008-December/010853.html,
> you may find the solution.
> Best Regards
> Sanjeev
>
> Dept. of Physics
> Bhavnagar University
> Gujarat
>
>
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