[Pw_forum] Unit cell and atomic position optimization

[Lazaro Calderin]

Hello every one!

I got pwscf running on a SUN cluster a while ago and I have started
doing some optimization of both unit cell parameters and atomic
positions in a hexagonal system (hydroxyapatite) to compare with LCAO
results. I have a problem similar to the one posted by Yanming Ma in his
last message. That is: pwscf does not converge to the a given pressure.
I tried increasing the mass of the unit cell to damp the oscillations
between negative and positive values of the pressure but it did not work
neither. I would be interested in any suggestions on how to perform
relaxation of unit cell parameters and atomic positions at the same time
in non-cubic systems using pwscf. I am trying to avoid the approach of
fitting of total energies for different geometries to the solid equation
of states. 

Thanks in advance,
Lazaro