[ase-users] PreconLBFGS and broken symmetry

[Noam Bernstein]

> On May 24, 2017, at 6:05 AM, Jens Jørgen Mortensen via ase-users <ase-users at listserv.fysik.dtu.dk> wrote:
> 
> Den 24-05-2017 kl. 11:48 skrev James Kermode:
>> Hi Jens Jorgen
>> 
>> Glad to hear its fast for your problem - typical speed up for DFT is 2-10x depending on system size and bonding type.
>> 
>> I’ve not tested it with symmetry, so this does look like a bug. This is happening at the initial stage when PreconLFGS is doing a couple of trial displacements to determine the energy scale of the problem, and it seems these displacements violate the symmetry. How is symmetry implemented in the other optimisers?
> 
> The other optimizer don't know anything about symmetry.  They just move the atoms along the forces and that seems to just work.  Maybe the trial step could be along the initial forces?  But if you need to do more than one trial step then I don't know!

Another possibility it to use my symmetrizing calculator (which uses spglib) to symmetrize the trial step (won’t work if it's orthogonal to the symmetry allowed displacement subspace).

								Noam


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Noam Bernstein, Ph.D.
Center for Materials Physics and Technology
U.S. Naval Research Laboratory
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