[Pw_forum] new unit-cell volume in variable cell relaxation

Eduardo Ariel Menendez Proupin eariel99 at gmail.com
Tue Mar 17 14:39:59 CET 2009

When doing variable cell relaxation it is useful to have the current volume
of the variable cell. This is reported in the output when
cell_dynamics='damp-w', e.g. in a line as the following
 new unit-cell volume =   3705.0385 (a.u.)^3

However, when cell_dynamics='bfgs' the cell volume is not reported (pw.x of
version 4.0.4 ).

I see in the text that bfgs is still experimental. If interesting for
debuging the code, I can supply an input  case where the relaxation fails .
In this case, in the 3rd bfgs step,

   WARNING: integrated charge=   140.52433035, expected=   288.00000000

     from electrons : error #         1
     charge is wrong

I suspect the bgfs made drastic change and the electronic calculation went
crazy. With damped dynamics it works smoothly.

Best regards

Eduardo Menendez
Departamento de Fisica
Facultad de Ciencias
Universidad de Chile
Phone: (56)(2)9787439
URL: http://fisica.ciencias.uchile.cl/~emenendez
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