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[Andrey Chibisov <andreichibisov@yandex.ru>]

Post my input file for beta Cristobalite:
ndtset 4

#Optimization of the lattice parameters
enunit 1
optcell 1
ionmov  3
tolmxf  5.0d-4
ntime  500
dilatmx 1.1
ecutsm  0.5

#Definition of the k-point grids
kptopt 1          # Option for the automatic generation of k points, taking
                  # into account the symmetry
nshiftk 1
shiftk  0.0 0.0 0.0

ngkpt1  2 2 2  
ngkpt2  4 4 4 
ngkpt3  6 6 6 
ngkpt4  8 8 8  

getwfk -1         # This is to speed up the calculation, by restarting
                  # from previous wavefunctions, transferred from the old 
                  # to the new k-points.

#Definition of the unit cell
spgroup 227
acell 3*13.52856
angdeg 90 90 90
rprim  0.0  0.5  0.5   # FCC primitive vectors (to be scaled by acell)
       0.5  0.0  0.5   
       0.5  0.5  0.0

#Definition of the atom types
ntypat 2          # There is only one type of atom
znucl 14 8
zion   4 6         # The keyword "znucl" refers to the atomic number of the 
                  # possible type(s) of atom. The pseudopotential(s) 
                  # mentioned in the "files" file must correspond
                  # to the type(s) of atom. Here, the only type is Silicon.
                         

#Definition of the atoms
natom 2           # There are two atoms
typat 1 2 # 1=Si 2=O
xred
    0.125  0.125  0.125 #Si
    0.000  0.000  0.000 #O
 
#Definition of the planewave basis set
ecut 30.0         # Maximal kinetic energy cut-off, in Hartree

#Definition of the SCF procedure
nstep 500          # Maximal number of SCF cycles
toldfe 1.0d-6     # Will stop when, twice in a row, the difference 
                  # between two consecutive evaluations of total energy 
                  # differ by less than toldfe (in Hartree)   

22.10.08, 10:56, "Anglade Pierre-Matthieu" <anglade@gmail.com>:

> Hi,
> Could you please post your input file ?
> Theoretically (and in practice (see test 24 in the v3 serie)) abinit
> can perform your calculation in spgroup 227 without problem. Thus, it
> could be quite helpful to see your input file in order to know what
> the problem could be.
> regards
> PMA
> On Wed, Oct 22, 2008 at 7:04 AM, Andrey Chibisov
> <andreichibisov@yandex.ru> wrote:
> > Can you help me with unit cell of Cristobalite?
> > Data for Cristobalite from site 
> > http://rruff.geo.arizona.edu/AMS/amcsd.php (American Mineralogist Crystal 
> > Structure Database) is:
> >
> > Title               Cristobalite
> > Lattice type        F
> > Space group name    Fd-3m
> > Space group number  227
> > Setting number      1
> >
> > Lattice parameters
> >   a        b        c       alpha    beta     gamma
> >  7.16600  7.16600  7.16600  90.0000  90.0000  90.0000
> > Unit-cell volume = 367.985229
> > Structure parameters
> >                       x          y          z          g          B
> >   1 Si  Si          0.12500    0.12500    0.12500    1.000    3.335
> >   2 O   O           0.00000    0.00000    0.00000    1.000    7.146
> >
> > In the input abinit file I write:
> > spgroup 227
> > For the primitive vectors of the lattice form a FCC lattice:
> >  rprim
> >        0.0 0.5 0.5
> >        0.5 0.0 0.5
> >        0.5 0.5 0.0
> > However the abinit gives out:
> > Unit cell is not primitive?
> > In what is my error?
> >
> > --
> > Andrey Chibisov.
> > Candidate of Science,
> > Structural Ceramics Laboratory
> > Institute of Geology and Nature Management
> > Far Eastern Branch of Russian Academy of Sciences
> >
> -- 
> Pierre-Matthieu Anglade

-- 
Andrey Chibisov.
Candidate of Science,
Structural Ceramics Laboratory
Institute of Geology and Nature Management 
Far Eastern Branch of Russian Academy of Sciences

ndtset 4

#Optimization of the lattice parameters
enunit 1
optcell 1
ionmov  3
tolmxf  5.0d-4
ntime  500
dilatmx 1.1
ecutsm  0.5

#Definition of the k-point grids
kptopt 1          # Option for the automatic generation of k points, taking
                  # into account the symmetry
nshiftk 1
shiftk  0.0 0.0 0.0

ngkpt1  2 2 2  
ngkpt2  4 4 4 
ngkpt3  6 6 6 
ngkpt4  8 8 8  

getwfk -1         # This is to speed up the calculation, by restarting
                  # from previous wavefunctions, transferred from the old 
                  # to the new k-points.

#Definition of the unit cell
spgroup 227
acell 3*13.52856
angdeg 90 90 90
rprim  0.0  0.5  0.5   # FCC primitive vectors (to be scaled by acell)
       0.5  0.0  0.5   
       0.5  0.5  0.0

#Definition of the atom types
ntypat 2          # There is only one type of atom
znucl 14 8
zion   4 6         # The keyword "znucl" refers to the atomic number of the 
                  # possible type(s) of atom. The pseudopotential(s) 
                  # mentioned in the "files" file must correspond
                  # to the type(s) of atom. Here, the only type is Silicon.
                         

#Definition of the atoms
natom 2           # There are two atoms
typat 1 2 # 1=Si 2=O
xred
    0.125  0.125  0.125 #Si
    0.000  0.000  0.000 #O
 
#Definition of the planewave basis set
ecut 30.0         # Maximal kinetic energy cut-off, in Hartree

#Definition of the SCF procedure
nstep 500          # Maximal number of SCF cycles
toldfe 1.0d-6     # Will stop when, twice in a row, the difference 
                  # between two consecutive evaluations of total energy 
                  # differ by less than toldfe (in Hartree)