[Wien] Problems with PORT minimization!

[L. D. Marks]

The "***false convergence***" means that the algorithm could not find a
location with a better energy consistent with the forces that you are
giving it. This may not be an issue, since the numerical accuracy of
the energies and forces in Wien is limited. Unfortunately you don't
provide all the information that is needed to diagnose your problem:
	1) Are your energies/charges etc well converged?
	2) Is it a CXZ spacegroup (in which case there are other problems)

Beyond this, there is a basic point. You have fixed the positions of your
central Pt atoms, so it is quite reasonable that the forces do not go to
zero at the (constrained) energy minimum.

On Mon, 18 Oct 2004, Timo Jacob wrote:

> Hello,
>
> I try to otimize the structure of a 5 layer slab (1x1)  including 3 central Pt
> layers and an oxygen layer at each surface.
> For my calculations I use an energy cutoff of 15 Ry (for an initial structure
> optimization) and the central Pt layer is fixed during the geometry
> optimization.
> Using the PORT option with the *.inM input attached below,
> the total energy mostly decreases but the forces seem to converge to finite
> numbers
> :FOR002 -38.535
> :FOR003  16.344
> and after 3-4 geometry iterations with same forces the geometry optimization
> stops with stop_forces_small. However, *.outputM contains the line
> ****false convergence*****.
>
> Any suggestions?
>
> Thanks in advance.
>
> ------------- *.inM -------------
> PORT 2.0
> 0 0 0 1.0
> 1.0 1.0 1.0 1.0
> 1.0 1.0 1.0 1.0
> ----------------------------------
>
> ------------ *.in1 ---------------
> WFFIL        (WFPRI, SUPWF)
>   3.900000   10    4 (R-MT*K-MAX; MAX L IN WF, V-NMT
>  -.22515   6   0      global e-param with N other choices, napw
>  0   -0.407     0.000 CONT 1
>  1   -0.226     0.000 CONT 1
>  1   -3.803     0.000 CONT 1
>  2   -0.167     0.000 CONT 1
>  3   -0.176     0.000 CONT 1
>  3   -4.858     0.000 CONT 1
>  -.22515   7   0      global e-param with N other choices, napw
>  0   -0.452     0.000 CONT 1
>  1   -0.283     0.000 CONT 1
>  1   -3.872     0.000 CONT 1
>  2   -0.240     0.000 CONT 1
>  2   -1.471     0.000 CONT 1
>  3   -0.212     0.000 CONT 1
>  3   -4.930     0.000 CONT 1
>  -.22515   3   0      global e-param with N other choices, napw
>  0   -0.367     0.000 CONT 1
>  0   -1.468     0.000 CONT 1
>  1   -0.292     0.000 CONT 1
> K-VECTORS FROM UNIT:4   -9.0       2.5      emin/emax window
> ----------------------------------
>
>
> --
> Dr. Timo Jacob                       Phone : ++49-30-8413 4816
> Fritz-Haber-Institut                   Fax   : ++49-30-8413 4701
>     der Max-Planck-Gesellschaft
> Faradayweg 4-6                      e-mail: jacob at fhi-berlin.mpg.de
> D-14 195 Berlin-Dahlem           Germany
> ----------------------------------------------------------------------
>               WWW: http://www.fhi-berlin.mpg.de/th/th.html
>
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
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>

-----------------------------------------------
Laurence Marks
Department of Materials Science and Engineering
MSE Rm 2036 Cook Hall
2225 N Campus Drive
Northwestern University
Evanston, IL 60201, USA
Tel: (847) 491-3996 Fax: (847) 491-7820
mailto:L-marks at northwestern.edu
http://www.numis.northwestern.edu
-----------------------------------------------