[Wien] Problem with geometry minimzation

[Laurence Marks]

This almost always means that the user (you) has set the IDFT problem
up incorrectly -- GIGO.

Have you read the optimization notes at
http://www.wien2k.at/reg_user/textbooks/ ? Do you have almost touching
spheres, bad RKMAX, k-points etc?

On Tue, Nov 2, 2010 at 1:53 AM, Saeed Bahramy <bahramy at riken.jp> wrote:
> Dear all,
>
> I'm trying to do geometry minimization for  atoms inside a hexagonal
> unitcell. For all atoms, I have set RMT to 2.5 a.u. and the minimization has
> been executed using the following command:
> min_lapw -I -j "run_lapw -I -fc 1.0 -ec 0.0001 -i 40"
>
> After few steps, the job stops with the following warning message:
>  :WARNING you might have inconsistent Forces/Energies
>
> The forces in the case.scf_mini look like:
>
>
> ******************************************************
>                                           * MULTISECANT MIXING OPTIONS
>                   *
>                                           * NFL Limit   0.100000
>                   *
>                                           * Diag Parm   0.000500
>                   *
>                                           * Standard Increase/Decrease
> Bounds                  *
>                                           * Plane Wave SQRT Dynamic
> Rescaling                  *
>                                           * Max Number of Memory Steps    8
>                    *
>
> ******************************************************
>
>                                     :PLANE:  INTERSTITIAL TOTAL     16.38294
> DISTAN  0.239D-05 %
>                                     :CHARG:  CLM CHARGE   TOTAL      8.54710
> DISTAN  0.270D-06 %
>                                                :REDuction and DMIX in Broyd:
>    1.1000    0.2000
>                                       :INFO :  Dynamic rescale   0.718D+00
>  0.100D+01  0.500D+01
>                                               :INFO :  Number of Memory
> Steps    3 Skipping    0
>                               :INFO :  Bounds         0.304D-01  0.200D+00
>  0.108D+00  0.304D-01
>                            :DIRM :  MEMORY 3/8 RESCALE  0.718 RED  0.983
> PRED  0.993 NEXT  0.923
>                                          :INFO :  DMIXM and Projections
> 0.304D-01  0.923D+00
>                              :DIRP :  |BROYD|= 0.488D-06 |PRATT|= 0.725D-07
> ANGLE=  41.0 DEGREES
>                              :DIRB :  |BROYD|= 0.495D-06 |PRATT|= 0.824D-07
> ANGLE=  44.6 DEGREES
>                                                                   MSEC1
> MIXING SCHEME WITH 0.030
>
> .....
>
>
>                                    :ENE  : ********** TOTAL ENERGY IN Ry =
>    -115360.01623084
>
>       TOTAL FORCE IN mRy/a.u. = |F|     Fx             Fy             Fz
>    with/without FOR
>       :FOR001:   1.ATOM         32.478          0.000          0.000
> 32.478 total forces
>       :FOR002:   2.ATOM          0.094          0.000          0.000
> -0.094 total forces
>       :FOR003:   3.ATOM          0.687          0.000          0.000
>  0.687 total forces
>
>                                        TOTAL FORCE WITH RESPECT TO GLOBAL
> CARTESIAN COORDINATES:
>       :FCA001:   1.ATOM                         0.000          0.000
> 32.478 total forces
>       :FCA002:   2.ATOM                         0.000          0.000
> -0.094 total forces
>       :FCA003:   3.ATOM                         0.000          0.000
>  0.687 total forces
>
>                                        TOTAL FORCE WITH RESPECT TO THE
> GLOBAL COORDINATE SYSTEM:
>       :FGL001:   1.ATOM                 0.000000000     0.000000000
>  32.478000000 total forces
>       :FGL002:   2.ATOM                 0.000000000     0.000000000
>  -0.094000000 total forces
>       :FGL003:   3.ATOM                 0.000000000     0.000000000
> 0.687000000 total forces
>  :WARNING you might have inconsistent Forces/Energies
>
> As you can see, the forces on atom #2 and #3 are quite small , The only
> problem is atom #1 on which the total force is rather large.
>
> My initial case.inM is as follows
>
> PORT 2.00 0.35      # PORT/NEWT;  tolf, Initial Trust Radius
> 0.0 0.0 1.0 1.0   #Atom    1 Generated by pairhess
> 0.0 0.0 1.0 1.0   #Atom    2 Generated by pairhess
> 0.0 0.0 1.0 1.0   #Atom    3 Generated by pairhess
>
> I have done additional calculations using NEW1 and NEWT methods, but so far
> no success! No matter what method I use, the total force remains as large as
> ~30 mRy/a.u..
>
> The muffin tins are well separated from each other and there is sufficient
> distance  between them for atomic relaxation.
> I'm wondering if somebody know how to fix this problem.
>
> Thanks,
> Saeed Bahramy
>
>
>
>
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>



-- 
Laurence Marks
Department of Materials Science and Engineering
MSE Rm 2036 Cook Hall
2220 N Campus Drive
Northwestern University
Evanston, IL 60208, USA
Tel: (847) 491-3996 Fax: (847) 491-7820
email: L-marks at northwestern dot edu
Web: www.numis.northwestern.edu
Chair, Commission on Electron Crystallography of IUCR
www.numis.northwestern.edu/
Electron crystallography is the branch of science that uses electron
scattering and imaging to study the structure of matter.