Very high forces on (experimentaly) relaxed geometries

Matt W MattWa... at gmail.com
Mon Nov 14 09:24:02 CET 2016


Hi,

I'd suggest you double,triple, quadruple check your cell parameters and 
geometry before anything else. It seems to me likely that somehow you have 
ovelapping atoms in periodic images.

Matt

On Sunday, November 13, 2016 at 6:32:02 PM UTC, Daniele Fontanari wrote:
>
> Dear CP2K users
>
> I'm very new to the software and DFT in general.
> Hope this is the right place to ask this question.
>
> I'd like to use CP2K to find structures of solids through geometry 
> optimization runs.
> I thought that a good strategy for preliminary calculations was to take a 
> known structure (a crystal whose atom positions are known) and run a 
> geometry optimization on it.
> My hope would be that it is possible to judge the "goodness" of the used 
> parameters by finding a relaxed structure close to the experimental.
>
> I tried to work with As2S3 (on a cell counting 8 atoms of As and 12 atoms 
> of S). My first optimization run managed to decrease a lot the energy but 
> completely destroyed the structure of the molecule, to understand what is 
> going on I tried to compute the forces on the atoms in my experimental 
> configuration and it appears that the total force is close to 0, the forces 
> on almost all the atoms are close to 0 except on 2 couples As As and S S 
> where there are enormous (but with 0 resultant) forces. Might this be an 
> anomaly source of the issue? 
>
> Is there someone that can help me? Did I use bad potentials/basis/xc 
> functional? Not fine enough grids? bad scf algorithms for this system?
>
> Thanks in advance.
>
>
>
> Here it is the cp2k code, I tried to keep it simple, a thing might be 
> useful to know is that without the OT method the SCF run oscillates and 
> apparently doesn't converge.
>
>  &GLOBAL
>   PROJECT As2S3_forces_calc
>   RUN_TYPE ENERGY_FORCE
>   PRINT_LEVEL LOW
> &END GLOBAL
> &FORCE_EVAL
>   METHOD QS
>   &SUBSYS
>     &CELL
>       ABC 11.475 9.577 4.256
>       ALPHA_BETA_GAMMA 90.0 90.68 90.0
>     &END CELL
>     &TOPOLOGY
>       COORD_FILE_FORMAT XYZ
>       COORD_FILE_NAME As2S3.xyz
>     &END TOPOLOGY
>     &KIND S
>       BASIS_SET TZV2P-GTH
>       POTENTIAL GTH-PADE
>     &END KIND
>     &KIND As
>       BASIS_SET TZV2P-MOLOPT-SR-GTH
>       POTENTIAL GTH-PADE
>     &END KIND
>   &END SUBSYS
>   &DFT
>     BASIS_SET_FILE_NAME BASIS_MOLOPT_UCL
>     BASIS_SET_FILE_NAME GTH_BASIS_SETS
>     POTENTIAL_FILE_NAME GTH_POTENTIALS
>     &SCF
>       SCF_GUESS RESTART
>       MAX_SCF 500
>       &OT .TRUE.
>       &END OT
>     &END SCF
>     &XC
>       &XC_FUNCTIONAL PADE
>       &END XC_FUNCTIONAL
>     &END XC
>   &END DFT
>   &PRINT
>     &FORCES ON
>     &END FORCES
>  &END PRINT
> &END FORCE_EVAL
>
> MY_BASIS_SETS is generated by
>
> $ cat GTH_BASIS_SETS BASIS_MOLOPT_UCL > MY_BASIS_SET
>
> As2S3.xyz:
> 20
> As2S3 (A,B,C)=(11.475 A, 9.577 A, 4.256 A) 
> (alpha,beta,gamma)=(90.0°,90.68°,90.0°)
> As     -2.87968     3.78519    -1.78703
> As     -6.29671     8.38345     4.62715
> As     -7.89374     4.70768     1.81738
> As     -1.28266     7.46095     1.02274
> As     -4.79404     4.29440     1.17991
> As     -4.38236     7.87423     1.66021
> As    -10.88155     5.01715    -0.01930
> As      1.70516     7.15148     2.85942
> S      -4.38840     2.75627    -0.40167
> S      -4.78799     9.41236     3.24179
> S      -9.07372     4.85434     3.77704
> S      -0.10268     7.31429    -0.93692
> S      -2.91319     3.98145     2.45383
> S      -6.26321     8.18718     0.38629
> S      -9.35548     3.43549     0.63482
> S       0.17909     8.73314     2.20530
> S      -0.92786     3.77410    -0.59081
> S      -8.24854     8.39453     3.43094
> S      -6.41721     2.99693     2.18326
> S      -2.75919     9.17170     0.65686
>
> the output (minus the SFC run and the timing informations) (look at atoms 
> 1-2 and 13-14!):
>  DBCSR| Multiplication 
> driver                                               XSMM
>  DBCSR| Multrec recursion 
> limit                                              512
>  DBCSR| Multiplication stack 
> size                                           1000
>  DBCSR| Maximum elements for images                                    
> UNLIMITED
>  DBCSR| Multiplicative factor virtual 
> images                                   1
>  DBCSR| Randmat seed                                                    
> 12341313
>  DBCSR| Multiplication size 
> stacks                                             3
>  DBCSR| Number of 3D layers                                               
> SINGLE
>  DBCSR| Use MPI memory 
> allocation                                              T
>  DBCSR| Use RMA 
> algorithm                                                      F
>  DBCSR| Use Communication 
> thread                                               T
>  DBCSR| Communication thread 
> load                                             87
>
>
>   **** **** ******  **  PROGRAM STARTED AT               2016-11-13 
> 18:55:20.125
>  ***** ** ***  *** **   PROGRAM STARTED ON                pinco.pallino
>  **    ****   ******    PROGRAM STARTED BY                              
> fontanar
>  ***** **    ** ** **   PROGRAM PROCESS ID                                 
> 92218
>   **** **  *******  **  PROGRAM STARTED IN /home/fontanar/
>
>  CP2K| version string:                    CP2K version 5.0 (Development 
> Version)
>  CP2K| source code revision 
> number:                                             
>  CP2K| cp2kflags: libint fftw3 libxc parallel mpi3 scalapack libxsmm 
> libgrid lib
>  CP2K|            deriv_max_am1=6 libint_max_am=8
>  CP2K| is freely available from                            
> https://www.cp2k.org/
>  CP2K| Program compiled at                        sam. nov.  5 22:37:09 
> CET 2016
>  CP2K| Program compiled on                                pinco.pallino
>  CP2K| Program compiled for                                            impi
>  CP2K| Data directory path                              
> /home/fontanar/cp2k/data
>  CP2K| Input file name                                          
> As2S3_forces.inp
> ...
> ...
> ...
>   Electronic density on regular grids:       -111.9999999385        
> 0.0000000615
>   Core density on regular grids:              111.9999999829       
> -0.0000000171
>   Total charge density on r-space grids:        0.0000000444
>   Total charge density g-space grids:           0.0000000444
>
>   Overlap energy of the core charge distribution:              
> 92.65065405538122
>   Self energy of the core charge distribution:               
> -398.65263980352455
>   Core Hamiltonian energy:                                    
> 105.34301297451202
>   Hartree energy:                                             
> 196.75976380751200
>   Exchange-correlation energy:                                
> -41.98461449052979
>
>   Total energy:                                               
> -45.88382345664910
>
>  ENERGY| Total FORCE_EVAL ( QS ) energy (a.u.):              
> -45.883823518851351
>
>
>  ATOMIC FORCES in [a.u.]
>
>  # Atom   Kind   Element          X              Y              Z
>       1      1      As        -18.30244796  -211.32223506    15.97738109
>       2      1      As         18.30955215   211.29826724   -15.97476790
>       3      1      As          0.03033974    -0.01535037    -0.02243601
>       4      1      As         -0.03033573     0.01527827     0.02246948
>       5      1      As         -0.06302510    -0.01399788    -0.06420679
>       6      1      As          0.06288169     0.01397371     0.06420477
>       7      1      As         -0.14318658     0.03752386     0.05230394
>       8      1      As          0.14341018    -0.03742549    -0.05230464
>       9      2      S          -0.04378316    -0.00438881     0.05507047
>      10      2      S           0.04393888     0.00437103    -0.05527078
>      11      2      S           0.15237734     0.06345576    -0.07781696
>      12      2      S          -0.15250573    -0.06340104     0.07801514
>      13      2      S          18.35579677   211.32485524   -15.99099261
>      14      2      S         -18.36294583  -211.30098802    15.98856882
>      15      2      S          -0.00508091    -0.11845479     0.09971522
>      16      2      S           0.00502481     0.11846616    -0.09985495
>      17      2      S           0.00456838    -0.00974499     0.01222899
>      18      2      S          -0.00470629     0.00972000    -0.01233881
>      19      2      S           0.00523795     0.02733833    -0.00734223
>      20      2      S          -0.00512153    -0.02726010     0.00737305
>  SUM OF ATOMIC FORCES          -0.00001092     0.00000307    
> -0.00000070     0.00001136
>
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