The ABINIT Users Mailing List ( CLOSED )

[Alex Huang <alex.zhen.huang@gmail.com>]

Dear Abinit users-

This is Alex and I am trying to extract interatomic force constants. I am
currently interested in Ti. 

For Ti I followed the example given in tutorial. The work of RF calculation
turn out to be OK. However, I have to use nshiftk=4 and   
 shiftk   0.0 0.0 0.5    # This gives the usual fcc Monkhorst-Pack grid
            0.0 0.5 0.0
            0.5 0.0 0.0
            0.5 0.5 0.5
Instead of recommended
nshiftk=1 and   
 shiftk   0.0 0.0 0.5    # This gives the usual fcc Monkhorst-Pack grid
by
http://www.abinit.org/documentation/helpfiles/for-v5.8/input_variables/varbas.html

Can anyone help me explain this?

On the other hand, even the calculation finished I have many warnings from 
the 
##############################################################
 hdr_check: WARNING -
  input nkpt=     128 not equal disk file nkpt=      50
  symafm:                               |  symafm:
    1  1  1  1  1  1  1  1              |    1  1  1  1  1  1  1  1
  symrel:                               |  symrel:
    1  0  0  0  1  0  0  0  1           |    1  0  0  0  1  0  0  0  1
   -1  0  0  0 -1  0  0  0 -1           |   -1  0  0  0 -1  0  0  0 -1
    0  1  0  1  0  0  0  0  1           |    0  1  0  1  0  0  0  0  1
    0 -1  0 -1  0  0  0  0 -1           |    0 -1  0 -1  0  0  0  0 -1
   -1  0  0  0 -1  0  0  0  1           |   -1  0  0  0 -1  0  0  0  1
    1  0  0  0  1  0  0  0 -1           |    1  0  0  0  1  0  0  0 -1
    0 -1  0 -1  0  0  0  0  1           |    0 -1  0 -1  0  0  0  0  1
    0  1  0  1  0  0  0  0 -1           |    0  1  0  1  0  0  0  0 -1
  typat:                                |  typat:
    1  1                                |    1  1
  so_psp  :                             |  so_psp  :
    1                                   |    1
  tnons:                                |  tnons:
     0.0000000   0.0000000   0.0000000  |     0.0000000   0.0000000   
0.0000000
    -0.3330000   0.3330000   0.5000000  |    -0.3330000   0.3330000   
0.5000000
    -0.3330000   0.3330000   0.5000000  |    -0.3330000   0.3330000   
0.5000000
     0.0000000   0.0000000   0.0000000  |     0.0000000   0.0000000   
0.0000000
    -0.3330000   0.3330000   0.5000000  |    -0.3330000   0.3330000   
0.5000000
     0.0000000   0.0000000   0.0000000  |     0.0000000   0.0000000   
0.0000000
     0.0000000   0.0000000   0.0000000  |     0.0000000   0.0000000   
0.0000000
    -0.3330000   0.3330000   0.5000000  |    -0.3330000   0.3330000   
0.5000000
   znucl:                               |   znucl:
   22.00                                |   22.00
  pseudopotential atom type  1:         |  pseudopotential atom type  1:
  pspso   0 pspxc   1                   |  pspso   0 pspxc   1
  pspdat 940714 pspcod    1 zion   4.0  |  pspdat 940714 pspcod    1 zion   
4.0
  xred:                                 |  xred:
     0.0000000   0.0000000   0.0000000  |     0.0000000   0.0000000   
0.0000000
     0.6670000   0.3330000   0.5000000  |     0.6670000   0.3330000   
0.5000000
#############################################################
                                                                              
 


The input file is listed below

# Crystalline AlAs : computation of the phonon spectrum

   ndtset   10
#Set 1 : ground state self-consistency

  getwfk1   0            # Cancel default
  kptopt1   1            # Automatic generation of k points, taking
                         # into account the symmetry
    nqpt1   0            # Cancel default
  tolvrs1   1.0d-12      # SCF stopping criterion (modify default)
  rfphon1   0            # Cancel default
 
#Q vectors for all datasets

#Complete set of symmetry-inequivalent qpt chosen to be commensurate
# with kpt mesh so that only one set of GS wave functions is needed.
#Generated automatically by running GS calculation with kptopt=1,
# nshift=0, shiftk=0 0 0 (to include gamma) and taking output kpt set
# file as qpt set. Set nstep=1 so only one iteration runs.

     nqpt   1            # One qpt for each dataset (only 0 or 1 allowed)
                         # This is the default for all datasets and must
                         #  be explicitly turned off for dataset 1.

#     qpt2   0.00000000E+00  0.00000000E+00  0.00000000E+00
#     qpt3   0.00000000E+00  0.00000000E+00  0.00000000E+00
#     qpt4   2.50000000E-01  0.00000000E+00  0.00000000E+00
#     qpt5   5.00000000E-01  0.00000000E+00  0.00000000E+00
#     qpt6   2.50000000E-01  2.50000000E-01  0.00000000E+00
#     qpt7   5.00000000E-01  2.50000000E-01  0.00000000E+00
#     qpt8  -2.50000000E-01  2.50000000E-01  0.00000000E+00
#     qpt9   5.00000000E-01  5.00000000E-01  0.00000000E+00
#     qpt10 -2.50000000E-01  5.00000000E-01  2.50000000E-01

       qpt2      0.00000000E+00  0.00000000E+00  0.00000000E+00
       qpt3      0.00000000E+00  0.00000000E+00  0.00000000E+00
       qpt4      2.50000000E-01  0.00000000E+00  0.00000000E+00
       qpt5      5.00000000E-01  0.00000000E+00  0.00000000E+00
       qpt6      2.50000000E-01  2.50000000E-01  0.00000000E+00
       qpt7      5.00000000E-01  2.50000000E-01  0.00000000E+00
       qpt8     -2.50000000E-01  2.50000000E-01  0.00000000E+00
       qpt9      5.00000000E-01  5.00000000E-01  0.00000000E+00
       qpt10     0.00000000E+00  0.00000000E+00  2.50000000E-01
       qpt11     2.50000000E-01  0.00000000E+00  2.50000000E-01
       qpt12     5.00000000E-01  0.00000000E+00  2.50000000E-01
       qpt13     2.50000000E-01  2.50000000E-01  2.50000000E-01
       qpt14     5.00000000E-01  2.50000000E-01  2.50000000E-01
       qpt15    -2.50000000E-01  2.50000000E-01  2.50000000E-01
       qpt16     5.00000000E-01  5.00000000E-01  2.50000000E-01
       qpt17     0.00000000E+00  0.00000000E+00  5.00000000E-01
       qpt18     2.50000000E-01  0.00000000E+00  5.00000000E-01
       qpt19     5.00000000E-01  0.00000000E+00  5.00000000E-01
       qpt20     2.50000000E-01  2.50000000E-01  5.00000000E-01
       qpt21     5.00000000E-01  2.50000000E-01  5.00000000E-01
       qpt22    -2.50000000E-01  2.50000000E-01  5.00000000E-01
       qpt23     5.00000000E-01  5.00000000E-01  5.00000000E-01


#Set 2 : Response function calculation of d/dk wave function 

    iscf2   -3         # Need this non-self-consistent option for d/dk
  kptopt2   2          # Modify default to use time-reversal symmetry
  rfphon2   0          # Cancel default
  rfelfd2   2          # Calculate d/dk wave function only
  tolvrs2   0.0        # Cancel default for d/dk
  tolwfr2   1.0d-18    # Use wave function residual criterion instead

#Set 3 : Response function calculation of Q=0 phonons and electric field pert.

  getddk3   2          # d/dk wave functions from last dataset
  kptopt3   2          # Modify default to use time-reversal symmetry
  rfelfd3   3          # Electric-field perturbation response only

#Sets 4-10 : Finite-wave-vector phonon calculations (defaults for all 
datasets)

   getwfk   1          # Use GS wave functions from dataset1
   kptopt   3          # Need full k-point set for finite-Q response
   rfphon   1          # Do phonon response
  rfatpol   1 2        # Treat displacements of all atoms
    rfdir   1 1 1      # Do all directions (symmetry will be used)
   tolvrs   1.0d-8     # This default is active for sets 3-10

#######################################################################
#Common input variables

#Definition of the unit cell
    acell   5.575 5.575 8.938   # This is equivalent to   2.95a 2.95a 4.73a
    angdeg  90 90 120
#    rprim   0.5  -0.866  0.0   # In lessons 1 and 2, these primitive vectors 
#            0.5  0.866  0.0   # (to be scaled by acell) were 1 0 0  0 1 0  0 0
1 
#            0.0  0.0  1.0   # that is, the default.

#Definition of the atom types
    ntypat   1         # There are two types of atom
    znucl   22     # 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, type 1 is the Titanium

#Definition of the atoms
    natom   2         # There are two atoms
    typat   1 1       # The first is of type 1 (Ti), the second is of type 2
(Ti).
                       
     xred   0.0  0.0  0.0
            0.667 0.333 0.5  

#Gives the number of band, explicitely (do not take the default)
    nband   40         

#Exchange-correlation functional

      ixc   1             # LDA Teter Pade parametrization

#Definition of the planewave basis set

     ecut   25.0           # Maximal kinetic energy cut-off, in Hartree

#Definition of the k-point grid
    ngkpt   4  4  4          
  nshiftk   4              # Use one copy of grid only (default)
                           #changed by Alex from 4 to 1
   shiftk   0.0 0.0 0.5    # This gives the usual fcc Monkhorst-Pack grid
            0.0 0.5 0.0
            0.5 0.0 0.0
            0.5 0.5 0.5

#Definition of the SCF procedure
     iscf   5          # Self-consistent calculation, using algorithm 5
    nstep   40         # Maximal number of SCF cycles$$ changed by Alex from 
25
to 125
   diemac   9.0