[CPMD-list] Atoms are very close?

Axel Kohlmeyer axel.kohlmeyer at theochem.ruhr-uni-bochum.de
Sat Mar 27 08:07:17 CET 2004 

On Fri, 26 Mar 2004, Erik Santiso wrote:

hello erik,

from looking at your input file, you have some serious problems:
     
- the surface option only works in combination with symmetry 0.
- the cell optimization _always_ works in 3 dimensions and
  _implicitely_ changes the cell symmetry to triclinic (IBRAV=14)
  unless you set ISOTROPIC CELL. (please have a look at the files
  sysin.F and setsys.F)
- for cell optimizations you need the stress tensor, but the stress
  tensor calculation for vanderbilt pseudopotential is (silently)
  broken in cpmd v3.7.x. which would explain the error you get.

so the best you can probably do, is run a series of jobs with
different cell geometries and pick the geometry that seems best.

if i am not mistaken, you have to be careful when comparing the 
energies directly, as the surface energy should also change if 
you change the box along the surface. perhaps somebody else
would like to comment on that (i'd be interested to learn more
about how to 'optimize a surface' properly as well).

axel kohlmeyer.

ES> 
ES> Hi,
ES> 
ES> I'm trying to do a cell optimization on a carbon surface. If I run the
ES> geometry optimization only, the program runs fine. However, when I add
ES> STEEPEST DESCENT CELL, I get this error:
ES> 
ES>  ATOM TYPE=           1  NUM=           1   9.39855555274434
ES>    8.13938721314203        15.0000000000000
ES>  ATOM TYPE=           1  NUM=           2   10.7412063475464
ES>    10.4649264196224        15.0000000000000
ES> 
ES> 
ES>  PROGRAM STOPS IN SUBROUTINE  SETSYS| ATOMS ARE VERY CLOSE
ES> 
ES> Even accounting for the PBC in x and y, the atoms are not really very
ES> close (the distance is roughly a C=C bond distance), unless cpmd is
ES> somehow changing the cell parameters I'm defining. Am I doing something
ES> wrong? The input I'm using is:
ES> 
ES> &CPMD
ES> 
ES>  OPTIMIZE GEOMETRY
ES>  MEMORY BIG
ES>  STEEPEST DESCENT CELL
ES>  CONVERGENCE CELL
ES>   0.01
ES> 
ES> &END
ES> 
ES> &SYSTEM
ES>  POISSON SOLVER MORTENSEN
ES>  SURFACE
ES>  SYMMETRY
ES>   8

the surface option only works in combination with symmetry 0.

the cell optimization 

ES>  CELL ABSOLUTE
ES>   24.1677142816811 18.6043136308668 30.0 0.0 0.0 0.0
ES>  CUTOFF
ES>   35
ES> 
ES> &END
ES> 
ES> &ATOMS
ES> 
ES> *C_BLYP_wcc.uspp FORMATTED NEWF NLCC
ES>  LMAX=P
ES>  48
ES>   1.889726625715786E-002  1.889726625715786E-002  0.000000000000000E+000
ES>    1.36154806105919        2.34443647273750       0.000000000000000E+000
ES>    1.36154806105919       -2.30664193946729       0.000000000000000E+000
ES>   -2.66640432221306       1.889726625715786E-002  0.000000000000000E+000
ES>   1.889724868269989E-002   4.66997567883990       0.000000000000000E+000
ES>    4.04684964990735        2.34443647273750       0.000000000000000E+000
ES>    4.04684964990735       -2.30664193946729       0.000000000000000E+000
ES>   1.889724868269989E-002  -4.63218114556969       0.000000000000000E+000
ES>   -4.00905511663714        2.34443647273750       0.000000000000000E+000
ES>   -4.00905511663714       -2.30664193946729       0.000000000000000E+000
ES>    1.36154806105919        6.99551488494229       0.000000000000000E+000
ES>   -2.66640432221306        4.66997567883990       0.000000000000000E+000
ES>    5.38950044433143        4.66997567883990       0.000000000000000E+000
ES>    5.38950044433143       1.889724868269989E-002  0.000000000000000E+000
ES>    5.38950044433143       -4.63218114556969       0.000000000000000E+000
ES>   -2.66640432221306       -4.63218114556969       0.000000000000000E+000
ES>    1.36154806105919       -6.95772035167209       0.000000000000000E+000
ES>   -6.69435670548531        2.34443647273750       0.000000000000000E+000
ES>   -6.69435670548531       -2.30664193946729       0.000000000000000E+000
ES>   1.889724868269989E-002   9.32105409104469       0.000000000000000E+000
ES>    4.04684964990735        6.99551488494229       0.000000000000000E+000
ES>   -4.00905511663714        6.99551488494229       0.000000000000000E+000
ES>    8.07480203317959        4.66997567883990       0.000000000000000E+000
ES>    8.07480203317959       1.889724868269989E-002  0.000000000000000E+000
ES>    8.07480203317959       -4.63218114556969       0.000000000000000E+000
ES>    4.04684964990735       -6.95772035167209       0.000000000000000E+000
ES>   -4.00905511663714       -6.95772035167209       0.000000000000000E+000
ES>   -8.03700749990939        4.66997567883990       0.000000000000000E+000
ES>   -8.03700749990939       1.889724868269989E-002  0.000000000000000E+000
ES>   -8.03700749990939       -4.63218114556969       0.000000000000000E+000
ES>   -2.66640432221306        9.32105409104469       0.000000000000000E+000
ES>    5.38950044433143        9.32105409104469       0.000000000000000E+000
ES>   -6.69435670548531        6.99551488494229       0.000000000000000E+000
ES>    9.41745282760368        6.99551488494229       0.000000000000000E+000
ES>    9.41745282760368        2.34443647273750       0.000000000000000E+000
ES>    9.41745282760368       -2.30664193946729       0.000000000000000E+000
ES>    9.41745282760368       -6.95772035167209       0.000000000000000E+000
ES>   -6.69435670548531       -6.95772035167209       0.000000000000000E+000
ES>    8.07480203317959        9.32105409104469       0.000000000000000E+000
ES>    12.1027544164518        6.99551488494229       0.000000000000000E+000
ES>    12.1027544164518        2.34443647273750       0.000000000000000E+000
ES>    12.1027544164518       -2.30664193946729       0.000000000000000E+000
ES>    12.1027544164518       -6.95772035167209       0.000000000000000E+000
ES>   -8.03700749990939        9.32105409104469       0.000000000000000E+000
ES>    13.4454052108759       -4.63218114556969       0.000000000000000E+000
ES>    13.4454052108759       1.889726663510319E-002  0.000000000000000E+000
ES>    13.4454052108759        4.66997567883990       0.000000000000000E+000
ES>    13.4454052108759        9.32105409104469       0.000000000000000E+000
ES> 
ES> &END
ES> 
ES> &DFT
ES> 
ES>   FUNCTIONAL BLYP
ES>   GC-CUTOFF
ES>    5.D-5
ES> 
ES> &END
ES> 
ES> Any help would be greatly appreciated. Thanks!
ES> 
ES> Erik.
ES> 
ES> -------------------------------------
ES> Vir prudens non contra ventum mingit.
ES> _______________________________________________
ES> CPMD-list mailing list
ES> CPMD-list at cpmd.org
ES> http://www.cpmd.org/mailman/listinfo/cpmd-list
ES> 
ES> 

-- 


=======================================================================
Dr. Axel Kohlmeyer                        e-mail: axel.kohlmeyer at rub.de
Lehrstuhl fuer Theoretische Chemie          Phone: ++49 (0)234/32-26673
Ruhr-Universitaet Bochum - NC 03/53         Fax:   ++49 (0)234/32-14045
D-44780 Bochum  http://www.theochem.ruhr-uni-bochum.de/~axel.kohlmeyer/
=======================================================================

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