[Pw_forum] optimization in crystal coordinates

[Louise Dash]

Andrea Vittadini wrote:
> Dear all,
> I'm doing some optimizations with pwscf.1.3.0 of some rhombohedral and
> hexagonal structures by entering atomic positions in "crystal" mode.
> What I find is that the final (and intermediate) atomic positions (also
> of the "crystal" type) appear to be messed up. 
> The same does not occur if I enter the "a0" coordinates computed by the
> program from my initial crystal positions, which means that my initial
> coordinates are correct.
> Anybody found this problem?
> Thanks,
> Andrea

Dear Andrea

I recently encountered the same problem (I think!) with pwscf 1.3.0 on 
monoclinic structures - the coordinates in the output file were wrong 
when I performed a relaxation, but the energies (and everything else) 
seemed OK.  As far as I could tell, the problem was *only* in the output 
file, not with the calculations themselves.

In the subroutine output_tau (file output_tau.f90) changing the line

call cryst_to_cart (nat, tau_out, at, 1)

to

call cryst_to_cart (nat, tau_out, bg, -1)

should sort this out - I think the conversion from crystal to cartesian 
coordinates was the wrong way round.

Hope this helps

Louise


-- 
Louise Dash
Laboratoire des Solides Irradies, Ecole Polytechnique
F-91128 Palaiseau, France
Tel +33 1 69 33 45 11
http://theory.polytechnique.fr