[ase-users] Energy increase in an optimization of cell

[Chang Liu]

Hello,


I am trying to optimize a thin film model. In one case (bulk_opt.1.py), I tried to optimize the cell parameters with the only constraint StrainFilter and in the other (bulk_opt.2.py), I tried to optimize with UnitCellFilter. The optimizer is BFGS with a maxstep of 0.01 Å for the first and 0.003 Å for the second. I added 7 Å vacuum below and above the film and the mask for the filters is [True,True,False,False,False,False], for I only want to optimize the x and y directions?. Strangely, in both cases, there is an increase in system energy while the energy should go down. The input files are attached. Did I make some mistake somewhere? Thanks a lot!?



Best wishes,
Chang Liu
----------------------------------------------------------
                        Chang Liu
                       PhD student
Fysikum, Albanova, Stockholm University
       S-106 91 Stockholm, Sweden
                 +46 767159891
    http://xsolasgroup.fysik.su.se/
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