Re: [Spglib-users] symmetrizing positions/cell vectors without altering cell?

[Noam B. <noa...@nr...>]

> On Sep 25, 2017, at 8:54 AM, Atsushi Togo <atz...@gm...> wrote:
> 
> Hi,
> 
>> Hi Togo - thanks for the quick response. Since I’m using the python
>> interface, which I don’t think has direct access to that routine, I’m not
>> sure, but I don’t think so, at least if I’m reading the documentation
>> correctly.
> 
> This for python,
> https://atztogo.github.io/spglib/python-spglib.html#standardize-cell <https://atztogo.github.io/spglib/python-spglib.html#standardize-cell>

thanks.

> 
> I'm sure that the paper's scheme works for atomic positions, but the
> paper doesn't mention about symmetrization of basis vectors if I
> remember correctly.

I don’t actually care about cell vectors right now, so if I could just get atomic positions symmetrized I’d be satisfied. 

> 
>> Let me put together an example based on the underlying C library, to take
>> the python interface out of the process, and I’ll post a followup.
> 
> But symmetrization is uneasy since it means the original input
> structure is distorted. So we have to determine how we want to
> symmetrize it. This makes me difficult to answer this type of
> question.
> 

I know what symmetry group I want the final configuration to be (it’s determined by spglib, in fact, just based on a loose symprec).  Basically, I think what I want is “no_idealize=0”, so move the atoms to symmetry required positions, but without touching the unit cell vectors at all.  Neither transforming into a primitive cell (what happens when to_primitive=1), nor transforming into a standard cell (what happens when to_primitive=0).  Just the original lattice vectors.  

								Noam


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Noam Bernstein, Ph.D.
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