[Pw_forum] Question on geometry relaxation

[Marcel Mohr]

Dear Opvu
>  I am trying to get the optimized geometry of monoclinic ZrO_{2} which have 4 parameters:
>  a =/ b =/ c and angle \beta = (c,a) =/ 90.
>
>  I don't know how to run a relaxation in which 4 parameters should be optimized at the same time. Is it right if I set the input file the same as the one for lattice constant calculation, but using calculation='md'?

I don't think that md is the right option for you, it is vc-relax.
I think (but I am definitely not sure about it) the difference is that 
with vc-relax time is a bit more arbitray and motions are damped.

I would repeat the relaxation from different starting geometries, to look, 
that the structure relaxes alway into the same geometry.

Alternatevely, you could do a lot of scf-calculations, and slightly change 
parameters a,b,c, \beta. In this 4-parameter space you try to 
minimize the total energy by some formular.

Cheers
Marcel