The ABINIT Users Mailing List ( CLOSED )

[yunhee.chang@kriss.re.kr]

Dear Abinit users,

I'm calculationg the In on Si(111) surface.

When I calculate the SCF cycle using fully relaxed atomic coordinates,
I cannot reach the same total energy and force compared to previous atomic 
relaxation calculation.
I didn't use the output WFK files, so I did SCF loop(just electonic, not 
atomic relaxation) for reaching ground state.
But their force is quite different..
I did force minimization around 0.001 eV/A,
but the force using relaxed coordinate is around 0.05 eV/A.

That means electronic SCF minimization has some problem..??
I increased the nband, but it's still same.
Do I have to choose another SCF cycle?
Would you give me any comments?

This is my input file.

==============================================================================
# Si(111)-4x1: 3BL slab
# A first step of atomic relaxation and total energy   
           
# Definition of occupation number
  occopt 3
  tsmear 0.0007
           
  nband 80 
           
#Definition of the unit cell    
  acell  2.105671378027334         3.647129810786902         1.488934510353547
  rprim 12.000000000000000         0.000000000000000         0.000000000000000
         0.000000000000000         2.000000000000000         0.000000000000000
         0.000000000000000         0.000000000000000        40.000000000000000
  chkprim 0              # This input variable allows to use non-primitive 
unit
                         # cells. Please, do not use it in other cases,
                         # you might miss a primitive cell, faster to handle.
           
#Definition of the atom types   
  ntypat 4           # There is only one type of atom
  znucl  49 14 14 1  # 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 Aluminum
                         
           
#Definition of the atoms
  natom 34                  # There are two atoms in this doubled cell
  typat 4*1 2*2 24*3 4*4    # These atoms are of type 1, that is, Aluminum
           
#Define the methodology to find the minimum
# ionmov  4              # Use the conjugate gradient algorithm
# ntime   30             # Maximum number of Broyden "timesteps"
# tolmxf  2.3d-5         # Stopping criterion for the geometry optimization : 
when
                         # the residual forces are less than tolmxf, the 
Broyden
                         # algorithm can stop
  natfix   12            # Fix the position of two symmetry-equivalent atoms
                         #  in doing the structural optimization
  iatfix   23 24 25 26 27 28 29 30 31 32 33 34
                         # Choose atoms 1 and 2 as the fixed atoms (see 
discussion)
  xangst                 # This keyword indicate that the location of the 
atoms
                         # will follow, one triplet of number for each atom
          4.81208922716606     0.00000000000000    18.96242987264197
           7.06126514599433     1.92997798069774    18.44619525314767
           9.54107109659771     0.00000000000000    18.50244627453926
          11.79858364903775     1.92997798069774    18.89701241902430
           0.93752037965351     1.92997798069774    17.98049761864093
           2.32517430108428     0.00000000000000    18.02460434084392
           0.06883434180141     1.92997798069774    15.70707828157864
           3.24669481604957     0.00000000000000    15.78259586066670
           6.69653954661645     1.92997798069774    15.76397531371200
          10.00849002402831     0.00000000000000    15.82662540146863
           1.09655439061929     0.00000000000000    14.82273027715486
           4.42974022967583     1.92997798069774    15.06176351602779
           7.80109204091853     0.00000000000000    14.94996234174407
          11.13930017846617     1.92997798069774    15.05651503941083
           1.10445225490822     0.00000000000000    12.50168835550348
           4.45211632475764     1.92997798069774    12.65811154209729
           7.79905934629338     0.00000000000000    12.59472103448601
          11.14927953093290     1.92997798069774    12.65600080591594
           2.24677893930407     1.92997798069774    11.79467792107055
           5.56327379886284     0.00000000000000    11.83351245642332 
           8.92328674704478     1.92997798069774    11.82214274533964
          12.23084192705557     0.00000000000000    11.81163195386842
           2.22854661337181     1.92997798069774     9.45492253503307
           5.57136653342950     0.00000000000000     9.45492253503307
           8.91418645348719     1.92997798069774     9.45492253503307
          12.25700637354488     0.00000000000000     9.45492253503307
           0.00000000000000     1.92997798069774     8.66701232378028
           3.34281992005769     0.00000000000000     8.66701232378028
           6.68563984011538     1.92997798069774     8.66701232378028
          10.02845976017307     0.00000000000000     8.66701232378028
           0.00000000000000     1.92997798069774     7.20149933085016
           3.34281992005769     0.00000000000000     7.20149933085016
           6.68563984011538     1.92997798069774     7.20149933085016
          10.02845976017307     0.00000000000000     7.20149933085016
          
# getwfk -1
           
#Definition of the k-point grids
  kptopt 1             # Option for the automatic generation of k points,
  ngkpt  2 8 1
  nshiftk 1              
  shiftk  0.5 0.5 0.0
           
#Exchange-correlation functional
  ixc 11               # GGA Perdew-Burke-Ernzerhof GGA functional
           
#Definition of the planewave basis set
  ecut 16.0            # Maximal kinetic energy cut-off, in Hartree
           
#Definition of the SCF procedure
  nstep 30             # Maximal number of SCF cycles
  toldff 2.3d-6     
# tolvrs 1.0d-6     
           
  prtden 1
  prtdos 1
  prtgeo 1
  prtwf 1
============================================================================


Best regards,
Yunhee Chang