The ABINIT Users Mailing List ( CLOSED )

[Masatake Takahashi <masatake@iis.u-tokyo.ac.jp>]

Dear kxyhu and ABINIT user

I think crystal structure of ferroelectric phase SBT has A2_1am orthorhombic 
structure, and natom should be 56 (Z=4). 
A2_1am (set 4 of Cmc2_1 in International Table Vol.A) structure of SBT is not 
primitive.

If you want to calculate SBT ground state using primitive cell(Z=2), 
monoclinic P2_1 (spgroup 4) symmetry should be used.


-------------------------
Masatake Takahashi
The university of Tokyo
masatake@iis.u-tokyo.ac.jp
-------------------------


kxyhu@yahoo.com.cn wrote:

> Hi everyone,
> 
> I am a new user of abinit. My material is  SrBi2Ta2O9. In the input file 
> the "spgroup" is 36 but in the output files the space group is 38. Moreover 
> the Angles of the  primitive cell are 90, 90, 24.89462,but in the output 
> file the Angles are 9.00000000E+01  9.00000000E+01  8.99822201E+01 degrees. 
> Could you please help me. my input files is below:
> 
> #Definition of the k-point grids
> kptopt 1         
> kptrlatt   6 0 0
>            0 6 0
>            0 0 6
> 
> #Definition of the unit cell
> acell 
> 10.43926  10.44250  47.3089
> brvltt -1
> angdeg   90 90  90
> spgaxor  6
> #Definition of the atom types
> ntype   4
> znucl   38  83  73  8
> spgroup 36
> #Definition of the atoms
> natom  28
> natrd   8
> 
> type  1  2  3 4 4 4 4 4 
> 
> xred
>     0.0     0.2567     0.0
>     0.4634  0.7764  0.19996
>     0.5104  0.7480  0.41482
>     0.5248  0.2892  0.0
>     0.5219  0.699   0.34187
>     0.7381  0.9923  0.25076
>     0.7554  0.9867  0.06964
>     0.7909  0.9807  0.58359
>