The ABINIT Users Mailing List ( CLOSED )

["Jin Zhang" <jin.zhang.pku@gmail.com>]

Dear chang,

Did you use different stop-criterions for scf cycle. I suspect the
difference comes from these settings:
-----
toldff 2.3d-6
# tolvrs 1.0d-6
----

BTW: maybe nstep=30 is a little small for a slab to reach convergence.

Best,

--
Jin Zhang
Dep. of Physics,
Peking University

On 11/23/06, yunhee.chang@kriss.re.kr <yunhee.chang@kriss.re.kr> wrote:
> Dear Abinit users,
>
> I'm calculating the In on Si(111) surface system.
>
> When I calculate the total energy using the fully relaxed atomic
> coordinates,
> I cannot reach the same total energy and force.
> I didn't use the previous WFK files,
> I just do SCF cycle to get ground state
> using relaxed atomic coordinates.
>
> The relaxed force is reached about 0.001 eV/A,
> but in SCF calculation using this coordinates,
> the force is reaching about 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