The ABINIT Users Mailing List ( CLOSED )

[Xavier Gonze <gonze@pcpm.ucl.ac.be>]

kxyhu@yahoo.com.cn wrote:
> Hello,
>
> When I use ABINIT 3.2.1 calculate the 5-0 nanotube ,the space is P1 (#1) in the output file.  
> However when use ABINIT 4.1.3 ,the space group is Pmm2 (#25). What  is my mistak ?

Please, do NOT use ABINITv3.2 : it is obsolete for a long time.

The difference between the two version lies in the tolerances
on the primitive lattice vectors and the atomic positions,
needed to recognize the symmetries.
There will be a FAQ about it soon (coming with v4.2).

Xavier




> This is my input file:
>
>
> # Crystalline 5_0 NanoTube
> #
> # Computation of the band structure.
> # First, a SCF density computation, then a non-SCF band structure calculation.
>
> ndtset 2
>
> #Dataset 1 : usual self-consistent calculation
> kptopt1 1          # Option for the automatic generation of k points,
>                    # taking into account the symmetry
> nshiftk1 1
> shiftk1  0.0 0.0 0.5  # These shifts will be the same for all grids
>          
> ngkpt1  1 1 5
> prtden1  1         # Print the density, for use by dataset 2
> toldfe1  1.0d-6
>
> #Dataset 2 : the band structure
> iscf2    -2
> getden2  -1
> kptopt2  -3
> nband2   70
> ndivk2   40 2 1    # 10, 12 and 17 divisions of the 3 segments, delimited
>                        # by 4 points.
> kptbounds2  0.0  0.0  0.0 # G point
>             0.0  0.0  0.5 # Z point 
>             0.0  0.5  0.5 # A point
>             0.0  0.5  0.0 # F point
>            
> tolwfr2  1.0d-12
> enunit2  1             # Will output the eigenenergies in eV 
>
>
> #Definition of the unit cell
> acell 37.807183 37.807183 8.052930  # 20A 20A 4.26A
> #rprim  1.0  0.0  0.0   # Hexgonal primitive vectors (to be scaled by acell)
> #       -0.5  0.866025  0.0   
> #       0.0  0.0  1.0
> angdeg 90.00 90.00 90.00
> #Definition of occupation numbers
> occopt 4
> tsmear 0.04
> #Definition of the atom types
> ntype 1           # There is one type of atom
> zatnum 6         # The keyword "zatnum" 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 20           # There are two atoms
> type 20*1         # They both are of type 1, that is, Silicon.
> xangst              # This keyword indicate that the location of the atoms
>                   # will follow, one triplet of number for each atom
>    1.95722     0.00000    -2.00000
>    0.60481     1.86142    -2.00000
>   -1.58342     1.15042    -2.00000
>   -1.58342    -1.15042    -2.00000
>    0.60481    -1.86142    -2.00000
>    1.58342     1.15042    -2.71000
>   -0.60481     1.86142    -2.71000
>   -1.95722     0.00000    -2.71000
>   -0.60481    -1.86142    -2.71000
>    1.58342    -1.15042    -2.71000
>    1.58342     1.15042    -4.13000
>   -0.60481     1.86142    -4.13000
>   -1.95722     0.00000    -4.13000
>   -0.60481    -1.86142    -4.13000
>    1.58342    -1.15042    -4.13000
>    1.95722     0.00000    -4.84000
>    0.60481     1.86142    -4.84000
>   -1.58342     1.15042    -4.84000
>   -1.58342    -1.15042    -4.84000
>    0.60481    -1.86142    -4.84000
>
> #Definition of the planewave basis set
> ecut 10.25         # Maximal kinetic energy cut-off, in Hartree
>
> #Definition of the SCF procedure
> nstep 99          # Maximal number of SCF cycles
> diemac 10.0  # For metals,simply put diemac to a very large value(10^6 is OK)
>
>
> Thank you,
> hu