[CP2K-user] [CP2K:13369] Problem with geometry optimization using LS_SCF

Torstein Fjermestad tfjer... at gmail.com
Mon May 25 11:45:51 UTC 2020


Dear Thomas,

Thanks for your fast reply.
I did not restart the Hessian matrix in test 3.
The LS_SCF section with all default made explicit, you can see here:
The complete input file is attached.
Thanks

Regards,
Torstein

     &LS_SCF
       LS_DIIS  F
       INI_DIIS  2
       MAX_DIIS  4
       NMIXING  2
       EPS_DIIS     1.0000000000000001E-01
       MAX_SCF  20
       EPS_SCF     9.9999999999999995E-08
       MIXING_FRACTION     4.5000000000000001E-01
       EPS_FILTER     9.9999999999999995E-08
       EPS_LANCZOS     1.0000000000000000E-03
       MAX_ITER_LANCZOS  128
       MU    -1.0000000000000001E-01
       FIXED_MU  F
       EXTRAPOLATION_ORDER  4
       S_PRECONDITIONER  ATOMIC
       PURIFICATION_METHOD  SIGN_MATRIX
       DYNAMIC_THRESHOLD  F
       NON_MONOTONIC  T
       MATRIX_CLUSTER_TYPE  ATOMIC
       SINGLE_PRECISION_MATRICES  F
       RESTART_WRITE  F
       RESTART_READ  F
       S_INVERSION  SIGN_SQRT
       SIGN_SQRT_ORDER  3
       REPORT_ALL_SPARSITIES  T
       PERFORM_MU_SCAN  F
       CHECK_S_INV  F
     &END LS_SCF


mandag 25. mai 2020 12.58.48 UTC+2 skrev tkuehne følgende:
>
> Dear Torstein, 
>
> apparently you are not exploiting the WF guess in your LS_SCF run, as you 
> have guessed. 
> Without an input I can only speculate, but by default EXTRAPOLATION_ORDER 
> is 4 within 
> LS_SCF and 3 for all other methods. Regarding test 3, did you also restart 
> the Hessian matrix? 
>
> Cheers, 
> Thomas
>
> Am 25.05.2020 um 12:34 schrieb Torstein Fjermestad <tf... at gmail.com 
> <javascript:>>:
>
> Dear all, 
>
> First some background for my question:
> I got computing hours on a cluster with GPUs. I did some tests with single 
> point calculations, and I found that linear scaling SCF ran about 5 times 
> faster than "normal" SCF for my system on that cluster. The total energy 
> between SCF and LS_SCF differed only by about 0.04 kJ mol-1; and I 
> therefore found the results encouraging. 
>
> I then went on to compare LS_SCF and "normal" SCF for geometry 
> optimizations on a machine without GPUs. I did three tests:
> Test 1: Single point calculation
> Test 2: Geometry optimization starting from the geometry in Test 1
> Test 3: Geometry optimization starting from the optimized geometry in Test 
> 2
>
> I used the following keywords in the LS_SCF section. 
>
> &LS_SCF
>   EPS_FILTER 1.0E-7
>   EPS_SCF    1.0E-7
> &END
>
> At the beginning of the attached output files the complete input is 
> echoed. 
>
> I now describe the results of the tests.
>
> Test 1: Single point calculation. The total energy differs by 0.05 kJ mol-1
>
> entry
>
> Total energy/ Ha
>
> wall time / s
>
> LS_SCF?
>
> 1
>
> -3499.00767
>
> 309
>
> yes
>
> 2
>
> -3499.00768
>
> 380
>
> no
>
>
> Test 2: Geometry optimization starting from the geometry in Test 1. 
> SCF_GUESS ATOMIC is used 
>
> entry
>
> Total energy, first geom / Ha
>
> max. grad of first step
>
> # geometry steps
>
> Total energy, optim geom / Ha
>
> wall time, s
>
> wall time / geom. step, s
>
> LS_SCF?
>
> 1
>
> -3499.00767
>
> 0.03493
>
> 54
>
> Did not converge within the requested wall time
>
> 7260 a
>
> 134
>
> yes
>
> 2
>
> -3499.00769
>
> 0.03613
>
> 123
>
> -3499.11153
>
> 4386
>
> 36
>
> no
> a Requested wall time in submit script
>
> In Test 2, the wall time per geometry step is much longer when LS_SCF is 
> used than when "normal" SCF is used. This is in spite of Test 1 showing 
> that LS_SCF is notably faster for a single point calculation. 
> Am I doing something wrong here?
> Is the start guess of the wavefunction at each geometry step perhaps not 
> adequate in the case of LS_SCF?
> How should I change the LS_SCF parameters in order to improve the 
> calculation?
>
> Test 3: Re-optimization of the optimized structure in Test 2 (entry 2). SCF_GUESS 
> ATOMIC is used 
>  
>
> entry
>
> Total energy, first geom / Ha
>
> max.grad of first step
>
> # geometry steps
>
> Total energy, optim geom / Ha
>
> wall time
>
> wall time / geom step
>
> LS_SCF?
>
> 1
>
> -3499.11150
>
> 0.00016
>
> 1
>
> -3499.11153
>
> 396
>
> 396
>
> no
>
> 2
>
> -3499.11147
>
> 0.00183
>
> 19
>
> Did not converge within the requested wall time
>
> 7260a
>
> 382
>
> yes
> a Requested wall time in submit script
>
> Not unexpectedly, in Test 3,  the geometry optimization with "normal" SCF 
> converges after 1 geometry step. 
> However, the geometry optimization with LS_SCF did not converge within two 
> hours and took only 19 geometry steps.
> I see that the max. gradient of the first geometry step is much higher in 
> the case of LS_SCF than in the case of "normal" SCF. 
> Are there some LS_SCF parameters I should adjust to check if the gradient 
> has converged?
>
> I would really appreciate help in this matter, because in the current 
> situation, I am not able to use LS_SCF for geometry optimizations. 
>
> Thanks and regards,
> Torstein Fjermestad
>
>   
>
>  
>
>
>
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> ==============================
> Thomas D. Kühne
> Dynamics of Condensed Matter
> Chair of Theoretical Chemistry
> University of Paderborn
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