[Pw_forum] vc-md question

[Guido Roma]

On Mon, 2006-01-30 at 10:10, Paolo Giannozzi wrote:

> there were some problems in previous versions with variable-cell 
> dynamics, but they should have been fixed in 2.1.5, AFAIK.
> Unfortunately nobody seems to be interested in maintaining
> the variable-cell stuff. I am seriously considering removing it
> altogether from future releases.
> 

Hi all,

I think it is useful in some cases, I used it for calculating formation
volume of defects. It is true that for this kind of duty one could
simply have a conjugate gradient (or BFGS) minimization of position
together with cell parameters.

Guido  

> > while the Parrinelo-Raman lagrangian would not run unless
> > nosym=.true. was stated. 
> 
> this is correct: since the Parrinello-Rahman may break the symmetry,
> you cannot rely on symmetry to reduce the number of k-points
> 
> Paolo