[ase-users] incorrectly ordered lattice vectors for vasp calculator

[Noam Bernstein]

Why not reorder the vectors only when writing the POSCAR (not in the underlying ASE object)?  I think of VASP as just an energy/force/stress calculate engine.    How is reformatting the ASE data into the form that VASP wants changing user input?  I think of it as similar to doing unit conversion for a calculator that expected positions in nm.  I guess the one thing it really would break is the use of VASP’s selective dynamics from ASE, but I think that ASE’s constraints are the better way to handle that kind of requirement.

Is it really a good idea to make ASE _users_ keep track of every idiosyncrasy of every calculator?  That would make it very difficult to write scripts that are general (w.r.t. calculator), which I think is one of the great strengths of ASE.

								Noam

> On Nov 5, 2018, at 2:12 AM, Offermans Willem via ase-users <ase-users at listserv.fysik.dtu.dk> wrote:
> 
> Dear ASE friends,
> 
> Changing the user input without notice is not a good idea, to my opinion.
> 
> A proposal for reorder with user confirmation request would be my idea.
> 
> 
> 
> Met vriendelijke groeten,
> Mit freundlichen Grüßen,
> 
> 
> Willem Offermans
> Researcher Electrocatalysis SCT
> VITO NV | Boeretang 200 | 2400 Mol
> Phone:+32(0)14335263 Mobile:+32(0)492182073 
> 
> Willem.Offermans at Vito.be <mailto:Willem.Offermans at Vito.be>
> <vito.jpg>
> 
>> On 5 Nov 2018, at 07:40, Jens Jørgen Mortensen via ase-users <ase-users at listserv.fysik.dtu.dk <mailto:ase-users at listserv.fysik.dtu.dk>> wrote:
>> 
>> On 11/1/18 4:49 PM, Noam Bernstein via ase-users wrote:
>>> Does anyone else think that the fact that the ase vasp calculator just passes the cell vectors to vasp, without reordering them if the triple scalar product is negative, is a bug?  VASP certainly refuses to run with such a set of lattice vectors.
>> 
>> 
>> I think ASE should raise an exception for that case - not try to reorder lattice vectors.
>> 
>> 
>> Jens Jørgen
>> 
>> 

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