[gpaw-users] Problem in an UnitCellFiltter calculation

[Honkala Karoliina]

Hi !

 I'm running an UnitCellFilter calculation for bulk CuO in plane wave
basis with gpaw version 0.9.1.10452 together with ASE 3.7.0.  The
calculation is running smoothly but despite that the simulation is not
yet converged I can see the the results will be wrong.

The bulk structure is generated with
bulk = crystal(['Cu','O'], [(0.25,0.25,0), (0.0, 0.42, 0.25)], spacegroup=15, setting=1,
cellpar=[al,bl,cl,90,beta, 90],pbc=True)

were the coordinates of Cu and O are taken from experimental work and lattice parameters al =
4.55 bl= 3.34 cl = 4.99 beta=99.506898 from previously published DFT
results which agree very well with experimentally determined lattice
parameters.

While the lattice parameters al and cl, and the angle  beta stay pretty intact upon the optimization of
the unit cell,  the lattice parameter bl changes dramatically being at the moment (unfinished calculation)  4.02  that is more than 0.5 Å  larger than the initial value. The calculation is still running but it is hard to see that it the value for bl would return close to the original and correct value.

CuO calculations should be done with PBE+U but leaving +U out should not affect this much.

Do you have any ideas what I could try to to get this right ?

The python script I'm using is attached.

Best regards,
                    Karoliina

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