Re: [Spglib-users] Extracting Structure Parameters

[Vyas R. <vya...@gm...>]

Here are the relevant data for the cell that I used (I didn't round it in
case that is helpful for you, sorry for the mess).

lattice: [[1.0849707126617432, 0.0, 0.0],
             [-1.0101166481035762e-05, 1.0850275754928589, 0.0],
             [0.00016498863988090304, -4.959173747920431e-05,
1.0849953889846802]]

positions: [[ 0.25729885,  0.20069639, -0.44741878],
            [-0.22380581, -0.29395782,  0.06201724]]

numbers: [1,1]

In case your question is just regarding my question being poorly phrased,
I'll try to clarify. What I referred to as the basis are just the
positions. In general, I could take any particle and apply the space group
operations, and I would get out a structure that has a copy of that
particle at each site dictated by those operations. However, that precise
set of output positions would depend on the position of the initial
particle to which I applied the operations. What I want to do, though, is
use the output of spglib to reproduce the exact input cell I originally fed
in.

As I understand it, spglib applies the transformation matrix and the origin
shift to transform the input cell into some unique frame in which it
determines the space group. My hope was that if I simply placed a particle
at the origin, applied the space group operations, and then subtracted the
origin shift and multiplied by the transformation matrix, I would get back
the exact lattice and positions that I fed into spglib. Should that work? I
have not been able to make it work, but I could very well be doing
something wrong.

On Wed, Jul 5, 2017 at 3:37 AM, Atsushi Togo <atz...@gm...> wrote:

> Hi,
>
> I need a bit more detailed information what you mean to answer. For
> example, what are lattice, basis, centred and exact positions?
>
> Togo
>
> On Wed, Jul 5, 2017 at 3:27 AM, Vyas Ramasubramani
> <vya...@gm...> wrote:
> > Hey everyone,
> >
> > I was wondering if there was any way to extract information about the
> > particular vector corresponding to a structure using spglib. By the
> > particular vector, I mean the (x, y, z) vector to which the space group
> > operations are applied in order to generate the positions. By providing a
> > lattice and a basis to spglib, I can get back the space group, but I am
> > wondering if there is a simple way to also get the vector that would
> > generate the exact positions I provided (perhaps rotated into a different
> > basis or centered at a different origin as per spglib's internal
> > representations). I have been trying to back it out of the standardized
> cell
> > constructed by spglib without success, so any thoughts would be
> appreciated.
> >
> > Thanks!
> > Vyas
> >
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>
>
> --
> Atsushi Togo
> Elements Strategy Initiative for Structural Materials, Kyoto university
> E-mail: atz...@gm...
>
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