[CP2K-user] [CP2K:10880] Re: diverging SCF wavefunction optimization for several nanocrystal-ligand systems (after they have been successfully relaxed)
Kat Newell
kat.n... at gmail.com
Thu Oct 25 16:00:42 UTC 2018
Thank you! I will give it a try.
Kat
> On 25 Oct 2018, at 17:56, Travis <polla... at gmail.com> wrote:
>
> Direct mixing is inefficient and the number of steps required for convergence grows rapidly with system size. Switch from DIRECT_P_MIXING to BROYDEN_MIXING or PULAY_MIXING to reduce the number of steps for convergence. See https://www.cp2k.org/_media/events:2015_cecam_tutorial:tong_qsscf.pdf
>
>
> On Wednesday, October 24, 2018 at 10:34:54 AM UTC-4, kat.... at gmail.com wrote:
> Hi,
> I have an issue with diverging SCF wavefunction optimization for 5 different systems of silicon nanocrystals with various ligands. So far this has not occurred (I have successfully simulated 20 other silicon nanocrystals with quite complicated ligands), so it does not seem to be consistent issue...
>
> For silicon nanocrystal with 235 atoms in the core and surface covered with Sulfur I use these parameters (extract from cp2k.out for energy_force):
>
> SCF PARAMETERS
> Density guess: RESTART
> --------------------------------------------------------
> max_scf: 200
> max_scf_history: 0
> max_diis: 4
> --------------------------------------------------------
> eps_scf: 5.00E-04
> eps_scf_history: 0.00E+00
> eps_diis: 1.00E-01
> eps_eigval: 1.00E-05
> --------------------------------------------------------
> level_shift [a.u.]: 0.00
> added MOs 100 0
> --------------------------------------------------------
> Mixing method: DIRECT_P_MIXING
> --------------------------------------------------------
> No outer SCF
>
> Number of electrons: 1780
> Number of occupied orbitals: 890
> Number of molecular orbitals: 4875
>
> Number of orbital functions: 4875
> Number of independent orbital functions: 4875
>
> Extrapolation method: initial_guess
>
> and I get this divergence in the optimization already after 2nd step:
>
> SCF WAVEFUNCTION OPTIMIZATION
>
> Step Update method Time Convergence Total energy Change
> ------------------------------------------------------------------------------
> 1 P_Mix/Diag. 0.40E+00 4.2 0.10908716 -2354.4136559975 -2.35E+03
> 2 P_Mix/Diag. 0.40E+00 5.0 0.44462605 -2354.4126056799 1.05E-03
> 3 P_Mix/Diag. 0.40E+00 5.1 0.53885704 -2354.3562265414 5.64E-02
> 4 P_Mix/Diag. 0.40E+00 5.0 3.07899832 -2352.5424379413 1.81E+00
> 5 P_Mix/Diag. 0.40E+00 5.0 33.29887563 -1891.1308608487 4.61E+02
> 6 P_Mix/Diag. 0.40E+00 5.3 30.17765973 4133.1886655512 6.02E+03
> 7 P_Mix/Diag. 0.40E+00 5.1 32.02311479 3797.3039280923 -3.36E+02
> 8 P_Mix/Diag. 0.40E+00 5.1 31.83587407 1215.6949983041 -2.58E+03
> 9 P_Mix/Diag. 0.40E+00 5.1 33.45037356 4635.2206528830 3.42E+03
> 10 P_Mix/Diag. 0.40E+00 5.1 30.96157640 2861.7052141337 -1.77E+03
> 11 P_Mix/Diag. 0.40E+00 5.1 29.36705839 2709.3853227498 -1.52E+02
> 12 P_Mix/Diag. 0.40E+00 5.5 31.13837241 3593.9217491598 8.85E+02
> 13 P_Mix/Diag. 0.40E+00 5.1 34.63292667 4412.8333731638 8.19E+02
> 14 P_Mix/Diag. 0.40E+00 5.1 30.85152040 4458.1077941490 4.53E+01
> .......
> Leaving inner SCF loop after reaching 200 steps.
>
>
> Electronic density on regular grids: -1779.9999999908 0.0000000092
> Core density on regular grids: 1779.9999997505 -0.0000002495
> Total charge density on r-space grids: -0.0000002402
> Total charge density g-space grids: -0.0000002402
>
> Overlap energy of the core charge distribution: 0.00000002843702
> Self energy of the core charge distribution: -5795.76572189967919
> Core Hamiltonian energy: 2938.96179612088508
> Hartree energy: 7673.11151856082142
> Exchange-correlation energy: -640.40137237794443
>
> Total energy: 4175.90622043252006
>
> *** WARNING in qs_scf.F:479 :: SCF run NOT converged ***
>
>
> ENERGY| Total FORCE_EVAL ( QS ) energy (a.u.): 55520.780056994452025
>
> But the system is fully relaxed, so the SCF run converged before (for the GEO_OPT) - see below the relaxation cp2k.out extract:
>
> -------- Informations at step = 25 ------------
> Optimization Method = CG
> Total Energy = -2354.4137112872
> Real energy change = -0.0000012787
> Decrease in energy = YES
> Used time = 475.723
>
> Convergence check :
> Max. step size = 0.0023939758
> Conv. limit for step size = 0.0030000000
> Convergence in step size = YES
> RMS step size = 0.0003373842
> Conv. limit for RMS step = 0.0015000000
> Convergence in RMS step = YES
> Max. gradient = 0.0004156999
> Conv. limit for gradients = 0.0004500000
> Conv. in gradients = YES
> RMS gradient = 0.0000585848
> Conv. limit for RMS grad. = 0.0003000000
> Conv. in RMS gradients = YES
> ---------------------------------------------------
>
> *******************************************************************************
> *** GEOMETRY OPTIMIZATION COMPLETED ***
> *******************************************************************************
>
> Reevaluating energy at the minimum
>
> Number of electrons: 1780
> Number of occupied orbitals: 890
> Number of molecular orbitals: 890
>
> Number of orbital functions: 4875
> Number of independent orbital functions: 4875
>
> Extrapolation method: ASPC
>
>
> SCF WAVEFUNCTION OPTIMIZATION
>
> ----------------------------------- OT ---------------------------------------
> Minimizer : DIIS : direct inversion
> in the iterative subspace
> using 7 DIIS vectors
> safer DIIS on
> Preconditioner : FULL_KINETIC : inversion of T + eS
> Precond_solver : DEFAULT
> stepsize : 0.15000000 energy_gap : 0.20000000
> eps_taylor : 0.10000E-15 max_taylor : 4
> ----------------------------------- OT ---------------------------------------
>
> Step Update method Time Convergence Total energy Change
> ------------------------------------------------------------------------------
> 1 OT DIIS 0.15E+00 3.5 0.00000227 -2354.4136673140 -2.35E+03
> 2 OT DIIS 0.15E+00 4.2 0.00000210 -2354.4136705162 -3.20E-06
> 3 OT DIIS 0.15E+00 4.1 0.00000166 -2354.4136799605 -9.44E-06
> 4 OT DIIS 0.15E+00 4.1 0.00000127 -2354.4136892114 -9.25E-06
> 5 OT DIIS 0.15E+00 4.1 0.00000111 -2354.4136936860 -4.47E-06
> 6 OT DIIS 0.15E+00 4.1 0.00000103 -2354.4136965337 -2.85E-06
> 7 OT DIIS 0.15E+00 4.1 0.00000092 -2354.4137006183 -4.08E-06
>
> *** SCF run converged in 7 steps ***
>
>
> Electronic density on regular grids: -1779.9999999998 0.0000000002
> Core density on regular grids: 1779.9999997509 -0.0000002491
> Total charge density on r-space grids: -0.0000002490
> Total charge density g-space grids: -0.0000002490
>
> Overlap energy of the core charge distribution: 0.00000002843702
> Self energy of the core charge distribution: -5795.76572189967919
> Core Hamiltonian energy: 1266.52936221037999
> Hartree energy: 2771.64162064259563
> Exchange-correlation energy: -596.81896159999383
>
> Total energy: -2354.41370061826001
>
> ENERGY| Total FORCE_EVAL ( QS ) energy (a.u.): -2354.413700618260009
>
> Please, anyone has an idea what am I doing wrong?
>
> Thank you in advance for any advice...
>
> best regards
>
> Katerina (Uni Amsterdam, NL)
>
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