[CP2K:9331] Optimizing Geometry AND Unitary cell

[Steve Schmerler]

On Aug 26 14:38 -0700, Henrique Junior wrote:
> Dear colleagues,
> I’m new to CP2K and I’m going to perform a geometric optimization in my 
> crystalline structure (to calculate vibrational frequencies, also using 
> CP2K). In my geometric optimization, I need to, also, optimize the size of 
> my unitary cell BUT I’d like to specify a range in which the cell is 
> allowed to expand (or contract, of course). Is this possible? Can someone 
> point me to any example?

If you need a special-purpose optimizer, you may have a look at ASE [1].
They have a CP2K calculator [2] for some time. The ASE structure
optimizer calls CP2K (or any other backend code) in each step to kick
off an SCF calculation to get energy and forces. 

You want to use one of their optimizers [3], together with the
UnitCellFilter constraint [4] to treat the cell. You would need to
modify the UnitCellFilter to meet you specific needs, or roll your own
entirely [5].

[1] https://wiki.fysik.dtu.dk/ase/
[2] https://wiki.fysik.dtu.dk/ase/ase/calculators/cp2k.html
[3] https://wiki.fysik.dtu.dk/ase/ase/optimize.html
[4] https://wiki.fysik.dtu.dk/ase/ase/constraints.html#the-unitcellfilter-class
[5] https://wiki.fysik.dtu.dk/ase/ase/constraints.html#making-your-own-constraint-class

best,
Steve