[Pw_forum] monoclinic system number of atom generated is incorrect

[Paolo Giannozzi]

You should first of all figure out if your data is for "unique axis b"
or "unique axis c". I think it is for the former case, so you should
specifiy "uniqueb=.true.". See also the input documentation of pw.x.
You also need to know the Wyckoff sites for your crystal:
   http://www.cryst.ehu.es/cgi-bin/cryst/programs/nph-wp-list

Paolo

On Wed, Jun 8, 2016 at 11:17 AM, Lorenzo Donà <lorechimica91 at hotmail.it> wrote:
> Good morning to everyone
> I am performing this calculation on a monoclinic system: Symmetry
> information:
> Monoclinic crystal system.
> Space group number     : 15
> Hall symbol            : -I 2ya
> Hermann-Mauguin symbol : I12/a1
> Symmetry equivalent sites:
>    1         x,        y,        z
>    2        -x,       -y,       -z
>    3    -x+1/2,        y,       -z
>    4     x+1/2,       -y,        z
>
> Lattice parameters:
>           a           b           c
>  23.8688000  11.1968000   7.8252000
>       alpha        beta       gamma
>  90.0000000  95.4750000  90.0000000
> Bravais lattice vectors :
>   1.0000000   0.0000000   0.0000000
>   0.0000000   0.4690977   0.0000000
>   0.4843601   0.2345489   0.1631733
>  in which the number of atom is 72 but in my pw.x output I found 80 atoms.
> this is my input:
>
> &control
>
>     calculation='relax'
>
>     pseudo_dir='/Users/lorenzodona/Downloads/espresso-5.4.0/pseudo/'
>
>     verbosity= high,
>
> /
>
>  &system
>
>     a= 23.8688, b= 11.1968, c= 7.8252, cosab= 0.417083157, space_group = 15,
>
>     nat=  20, ntyp= 4,
>
>     ecutwfc =15.0,
>
>     rhombohedral= .false.
>
> /
>
>  &electrons
>
>     diagonalization='david'
>
>     mixing_beta = 0.7
>
>     conv_thr= 1.0e-7
>
> /
>
>  &ions
>
>  ion_dynamics='bfgs'
>
>  /
>
> ATOMIC_SPECIES
>
> Zr 91.224 Zr.pbe-mt_fhi.UPF
>
> C 12.010 C.pbe-mt_fhi.UPF
>
> O 16.00  O.pbe-mt_fhi.UPF
>
> H 1.00   H.pbe-mt_fhi.UPF
>
> ATOMIC_POSITIONS crystal_sg
>
> Zr      0.8055700   0.2260400   0.1404400
>
> O       0.7837400   0.2764700   0.3778600
>
> O       0.7887800   0.0352700   0.0965300
>
> O       0.8863700   0.2930100   0.0648300
>
> O       0.7894200   0.4193200   0.0923400
>
> O       0.8721000   0.1295600  -0.7030000
>
> C       0.8994700   0.1401400   0.4427600
>
> C       0.9514400   0.0679000   0.4731700
>
> C       0.9682300  -0.0035900   0.3401200
>
> C       0.0168300  -0.0717400   0.3668600
>
> C      -0.2965000  -0.2104000  -0.0790000
>
> C      -0.7034500  -0.6656900   0.0788000
>
> H       0.9426100  -0.0042000   0.2174500
>
> H       0.0307000   0.8716500   0.2661000
>
> H       0.3320300   0.3845300   0.1396500
>
> H       0.6681300   0.8400300   0.8596200
>
> C       0.7500000   0.4711800   0.0000000
>
> C       0.7500000   0.9838200   0.0000000
>
> C       0.7500000   0.8516100   0.0000000
>
> C       0.7500000   0.6036500   0.0000000
>
>
> Can you tell me where I am making a mistake??
> thanks a lot
> dearly
> lorenzo
>
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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