[QE-users] Different crystal structure between pw.x and ph.in output files for non-centrosymmetric compund

[Paolo Giannozzi]

Nothing to worry about. It was corrected a few days ago:
  https://gitlab.com/QEF/q-e/commit/98d6147e9206ed0affe8415c3c4a2ad9f8eca60a

On Mon, Dec 17, 2018 at 7:01 PM Arena Konta <qe6user at gmail.com> wrote:

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> Hello,
>
> I try to do calculations for noncentrosymmetric superconductor CaIrSi3 (
> tetragonal BaNiSn3-type crystal
> structure, with space group I4mm (no. 107)) using QE 6.3:
>
> ************************************************************************
> &SYSTEM
>        ibrav = 0
> celldm(1)=7.90529
> nat=5
> ntyp=3
>
> /
>
>
>
>  CELL_PARAMETERS alat
>  1.000000000000000   0.000000000000000   0.000000000000000
>   0.000000000000000   1.000000000000000   0.000000000000000
>   0.500000000000000   0.500000000000000   1.180025338847321
>
>
>
>
> ATOMIC_POSITIONS (crystal)
> Ir   0.763090000000000   0.763090000000000   0.473820000000000
> Ca   0.409750000000000   0.409750000000000   0.180500000000000
> Si   0.650890000000000   0.150890000000000   0.698220000000000
> Si   0.150890000000000   0.650890000000000   0.698220000000000
> Si   0.000000000000000   0.000000000000000   0.000000000000000
>
>
> ******************************************************************************
>
> scf goes fine and I get at the beginning of the output:
>
>    bravais-lattice index     =            0
>      lattice parameter (alat)  =       7.9053  a.u.
>      unit-cell volume          =     582.9680 (a.u.)^3
>      number of atoms/cell      =            5
>      number of atomic types    =            3
>
>
>      celldm(1)=   7.905290  celldm(2)=   0.000000  celldm(3)=   0.000000
>      celldm(4)=   0.000000  celldm(5)=   0.000000  celldm(6)=   0.000000
>
>      crystal axes: (cart. coord. in units of alat)
>                a(1) = (   1.000000   0.000000   0.000000 )
>                a(2) = (   0.000000   1.000000   0.000000 )
>                a(3) = (   0.500000   0.500000   1.180025 )
>
>      reciprocal axes: (cart. coord. in units 2 pi/alat)
>                b(1) = (  1.000000  0.000000 -0.423720 )
>                b(2) = (  0.000000  1.000000 -0.423720 )
>                b(3) = (  0.000000  0.000000  0.847439 )
>
>
>
> But when I start ph.x calculation (in the same folder using exactly the
> same values) I get:
>
>
>      bravais-lattice index     =            0
>      lattice parameter (alat)  =       7.9053  a.u.
>      unit-cell volume          =     582.9680 (a.u.)^3
>      number of atoms/cell      =            5
>      number of atomic types    =            3
>
>
>
>      celldm(1)=   15.81058  celldm(2)=   Infinity  celldm(3)=    0.68783
>      celldm(4)=    0.00000  celldm(5)=    0.36346  celldm(6)=    0.00000
>
>      crystal axes: (cart. coord. in units of alat)
>                a(1) = (  1.0000  0.0000  0.0000 )
>                a(2) = (  0.0000  1.0000  0.0000 )
>                a(3) = (  0.5000  0.5000  1.1800 )
>
>      reciprocal axes: (cart. coord. in units 2 pi/alat)
>                b(1) = (  1.0000  0.0000 -0.4237 )
>                b(2) = (  0.0000  1.0000 -0.4237 )
>                b(3) = (  0.0000  0.0000  0.8474 )
>
>
> Why there are such differences in celldm?
>
> --
> with regards
>
> Arena Konta
> The Institute of Thermophysics in Novosibirsk Scientific Center
>
>
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-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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