[gpaw-users] Constraining the lattice constant

[Gaël Donval]

Hi Joao,

> Yes, I would like to fix the lattice completely, just let the atoms
> relax.

Then there is no problem: this is *exactly* what you get unless you
specifically choose to use MD in the NPT ensemble. Said the other way
around, if you don't do MD or if you don't work in the NPT ensemble,
the unit cell shouldn't change.

Best regards,
Gaël

> I am afraid if I put an Observer saying that I want the cell always
> the
> same, that GPAW will always try to change the cell and then the
> Observer
> changing it back and never get to the minimum energy.
> 
> Best regards,
> Joao