[CP2K:4577] Re: Quickstep: SCF Energy increasing after few outer-SCF cycles

SRKC Sharma Yamijala sharma... at gmail.com
Thu Aug 22 02:48:08 UTC 2013


Dear Matt,

Thank you for such a quick reply. I will do my calculation by changing the
pre-conditioner.

Just I would like to mention that the above two possibilities which you
have mentioned are unlikely for my case because the structure is an already
optimized one using other method (PBE) and as it is a quantum dot, it can't
be metallic. Any ways, I will do my calculation and let you know whether it
is working or not.

Thank you once again,
Sincerely,
Sharma.








********************************************************
*Chaitanya Sharma,*
*Prof. Bala and Prof. Pati'*s groups,
Chemistry and Physics Materials unit,
JNCASR, BANGLORE,
Lab:: (080-2208) 2581, 2809
https://sites.google.com/site/sharmasrkcyamijala/
*********************************************************


On Thu, Aug 22, 2013 at 12:05 AM, Matt W <MattWa... at gmail.com> wrote:

> Hi,
>
> this seems to occur in some systems, sorry no deep physical understanding
> of the problem - could well be that your geometry is not ideal / nearly
> metallic electronic structure. A sure sign is that the electron density
> projected onto the RS grid starts to get (significantly - losing noticable
> numbers of electrons) worse as the calculation goes on.
>
> FULL_ALL preconditioner is quite aggressive - pragmatically try switching
> to FULL_SINGLE_INVERSE for an ENERGY calculation until (very nearly)
> converged, then go back to FULL_ALL.  The speed gains (in SCF cycles) are
> probably only worth it for long MD runs anyway.
>
> Matt
>
> On Wednesday, August 21, 2013 2:54:12 PM UTC+1, Sharma SRK Chaitanya
> Yamijala wrote:
>>
>> Dear all CP2K users,
>>
>> I am trying to optimize a Graphene Quantum Dot using BLYP-DFT-D3/DZVP
>> method as implemented in CP2K. While optimizing I have observed that,  SCF
>> energy is decreasing (i.e. becoming more negative) at the beginning of the
>> run, but after few outer-SCF loops, the energy starts increasing and the
>> increment is going on and on if I am leaving the system to run.
>>
>> Also, I have observed that the inner-SCF energy has reached a convergence
>> (for this system) value  of ~ 10^(-5) after 2 outer-SCF cycles  (where my
>> EPS_SCF is 1.0E-6) and after the beginning of the 3rd outer-SCF tolerance
>> has increased to a value of ~ 10^(-3).
>>
>> I would like to get your suggestions on any way to avoid this convergence
>> issue. The input file and the output file (just before and after the 2nd
>> outer-SCF) are given below (hopping they may be help you in suggesting).
>>
>> Thank you all,
>> Sincerely,
>> Sharma.
>>
>> P.S: I have checked in the mailing list but I couldn't exactly found any
>> post on this issue (though there are on BOMD-energy increment etc.)
>>
>> *Input_file:*
>>
>> &FORCE_EVAL
>>
>>   METHOD Quickstep
>>
>>   &DFT
>>
>>     CHARGE = 0
>>     MULTIPLICITY = 2
>>     LSD # for odd number of electrons and specifying this keyword itself
>> enforces for spin-polarized calculations
>>
>>     BASIS_SET_FILE_NAME  BASIS_MOLOPT
>>     POTENTIAL_FILE_NAME  GTH_POTENTIALS
>>
>>     &MGRID
>>       CUTOFF 320
>>       NGRIDS 5
>>       REL_CUTOFF 40
>>     &END MGRID
>>
>>     &QS
>>       METHOD GPW
>>       EPS_DEFAULT 1.0E-10
>>     &END QS
>>
>>     &SCF
>>
>>       SCF_GUESS RESTART
>>       EPS_SCF 1.0E-6
>>       MAX_SCF 100
>>
>>       &OUTER_SCF
>>         EPS_SCF 1.0E-6
>>         MAX_SCF 500
>>       &END
>>
>>       &OT
>>         MINIMIZER CG
>>         PRECONDITIONER FULL_ALL
>>         ENERGY_GAP 0.001
>>         STEPSIZE 0.05
>>       &END
>>
>>     &END SCF
>>
>>     &XC
>>
>>       &XC_FUNCTIONAL BLYP
>>       &END XC_FUNCTIONAL
>>
>>       &XC_GRID
>>         XC_DERIV  SPLINE2
>>         XC_SMOOTH_RHO NN50
>>       &END XC_GRID
>>
>>       &vdW_POTENTIAL
>>
>>         DISPERSION_FUNCTIONAL PAIR_POTENTIAL # POTENTIAL_TYPE is alias to
>> DISPERSION_FUNCTIONAL
>>
>>
>>         &PAIR_POTENTIAL
>>           TYPE DFTD3
>>           PARAMETER_FILE_NAME  dftd3.dat
>>           REFERENCE_FUNCTIONAL BLYP
>>         &END PAIR_POTENTIAL
>>
>>       &END vdW_POTENTIAL
>>
>>     &END XC
>>
>>     &POISSON
>>       POISSON_SOLVER WAVELET
>>       PERIODIC NONE
>>     &END POISSON
>>
>>   &END DFT
>>
>>   &SUBSYS
>>
>>     &CELL
>>       ABC 38.0 38.0 38.0
>>       ALPHA_BETA_GAMMA  90.0 90.0 90.00
>>       PERIODIC NONE
>>     &END CELL
>>
>>     &TOPOLOGY
>>       &CENTER_COORDINATES
>>       &END
>>     &END
>>
>>     &COORD
>>      @INCLUDE gqd_270.xyz
>>     &END COORD
>>
>>     &KIND H
>>       BASIS_SET DZVP-MOLOPT-SR-GTH
>>       POTENTIAL GTH-BLYP-q1
>>     &END KIND
>>
>>     &KIND C
>>       BASIS_SET DZVP-MOLOPT-SR-GTH
>>       POTENTIAL GTH-BLYP-q4
>>     &END KIND
>>
>>     &KIND N
>>       BASIS_SET DZVP-MOLOPT-SR-GTH
>>       POTENTIAL GTH-BLYP-q5
>>     &END KIND
>>
>>   &END SUBSYS
>>
>> &END FORCE_EVAL
>>
>> &GLOBAL
>>   PROJECT au20_tetra_on_n-gqd
>>   RUN_TYPE GEO_OPT
>>   PRINT_LEVEL MEDIUM
>> &END GLOBAL
>>
>> &MOTION
>>   &GEO_OPT
>>     OPTIMIZER BFGS
>>     MAX_ITER   5000
>>     MAX_FORCE  1.00D-4
>>     TYPE MINIMIZATION
>>   &END
>>
>> &END MOTION
>>
>>
>> ###########################################################################################################################
>> *
>> *
>> *OUTPUT-FILE:*
>>
>>
>>     98 OT LS       0.54E-01    6.9                    -1982.8376246687
>>
>>   Trace(PS):                                 1174.9999638412
>>   Electronic density on regular grids:      -1174.9999638398
>> 0.0000361602
>>   Core density on regular grids:             1174.9999998887
>> -0.0000001113
>>   Total charge density on r-space grids:        0.0000360489
>>   Total charge density g-space grids:           0.0000360489
>>
>>     99 OT CG       0.54E-01   12.3     0.00000845     -1982.8383595833
>> -7.61E-05
>>
>>   Trace(PS):                                 1174.9999635922
>>   Electronic density on regular grids:      -1174.9999635907
>> 0.0000364093
>>   Core density on regular grids:             1174.9999998887
>> -0.0000001113
>>   Total charge density on r-space grids:        0.0000362980
>>   Total charge density g-space grids:           0.0000362980
>>
>>    100 OT LS       0.22E+00    6.9                    -1982.8383813757
>>
>>   *** SCF run NOT converged ***
>>
>>
>>   Electronic density on regular grids:      -1174.9999635907
>> 0.0000364093
>>   Core density on regular grids:             1174.9999998887
>> -0.0000001113
>>   Total charge density on r-space grids:        0.0000362980
>>   Total charge density g-space grids:           0.0000362980
>>
>>   Overlap energy of the core charge distribution:
>> 0.00005046108667
>>   Self energy of the core charge distribution:
>> -4271.91259980407449
>>   Core Hamiltonian energy:
>> 1351.88408937624945
>>   Hartree energy:
>> 1448.17384258600623
>>   Exchange-correlation energy:
>> -510.06161737575133
>>   Dispersion energy:
>> -0.92214661917833
>>
>>   Total energy:
>> -1982.83838137566136
>>
>>   outer SCF iter =    3 RMS gradient =   0.84E-05 energy =
>> -1982.8383813757
>>
>>   ----------------------------------- OT
>> ---------------------------------------
>>
>>   Allowing for rotations:  F
>>   Optimizing orbital energies:  F
>>   Minimizer      : CG                  : conjugate gradient
>>   Preconditioner : FULL_ALL            : diagonalization, state selective
>>   Precond_solver : DEFAULT
>>   Line search    : 2PNT                : 2 energies, one gradient
>>   stepsize       :    0.05000000
>>   energy_gap     :    0.00100000
>>
>>   eps_taylor     :   0.10000E-15
>>   max_taylor     :             4
>>
>>   mixed_precision    : F
>>
>>   ----------------------------------- OT
>> ---------------------------------------
>>
>>   Step     Update method      Time    Convergence         Total energy
>> Change
>>
>> ------------------------------------------------------------------------------
>>
>>   Trace(PS):                                 1174.9999628452
>>   Electronic density on regular grids:      -1174.9999628438
>> 0.0000371562
>>   Core density on regular grids:             1174.9999998887
>> -0.0000001113
>>   Total charge density on r-space grids:        0.0000370449
>>   Total charge density g-space grids:           0.0000370449
>>
>>      1 OT CG       0.50E-01   24.7     0.00073898     -1982.8383578477
>> 1.74E-06
>>
>>   Trace(PS):                                 1174.6089204778
>>   Electronic density on regular grids:      -1174.6089204763
>> 0.3910795237
>>   Core density on regular grids:             1174.9999998887
>> -0.0000001113
>>   Total charge density on r-space grids:        0.3910794124
>>   Total charge density g-space grids:           0.3910794124
>>
>>      2 OT LS       0.16E-01    6.8                    -1982.7669389193
>>
>>   Trace(PS):                                 1174.8781005916
>>   Electronic density on regular grids:      -1174.8781005901
>> 0.1218994099
>>   Core density on regular grids:             1174.9999998887
>> -0.0000001113
>>   Total charge density on r-space grids:        0.1218992986
>>   Total charge density g-space grids:           0.1218992986
>>
>>      3 OT CG       0.16E-01   12.3     0.00075231     -1982.7595972134
>> 7.88E-02
>>
>>
>>
>>
>>
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