[xcrysden] Space Group 63, base centered Orthorhombic Structure Problem

[Tone Kokalj]

On Wed, 2014-06-18 at 13:50 -0500, Sai Kumar Ramadugu wrote:

> 
> When I create an input file for PWSCF and view it in XCrysDen, it only
> shows two atoms (attached as figure1xsf.png), 

To be more precise, it shows two atoms in the conventional cell and this
is correct. Why? Because you specified only one atom (for the primitive
cell) in the pw.x input file. This implies that for base-centered cells
there are two atoms in the conventional cell, i.e. (in crystal
coordinates):

atom1  x     y      z
atom2  x+0.5 y+0.5  z

> whereas if I create the structure file using Materials Studio or
> VESTA, I see 6 atoms (attached as figure2vesta.jpeg).

I guess the difference is that the VESTA and MS take advantage of the
space-group info and use corresponding symmetry operations to generate
other symmetry-equivalent atoms. The pw.x does not do this and you need
to specify all the atoms within the primitive unit cell.

You may do a check: run pw.x on your input and then display the
structure from the output: xcrysden should show only one atom (because
in this case xcrysden will display the primitive cell).

Regards,

-- 
Anton Kokalj
J. Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia 
(tel: +386-1-477-3523 // fax:+386-1-477-3822)

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