[CP2K-user] [CP2K:16260] Re: Improve extrapolation between relaxation steps?
Matt Watkins
mattwatkinsuk at gmail.com
Thu Nov 18 08:34:56 UTC 2021
I've not played with smearing / OT, maybe someone else can suggest a good
setup and whether it is recommended.
If there is a modest gap I would expect to get convergence in ~10 DIIS / 20
CG SCF steps after a few relaxation steps.
Matt
On Wednesday, 17 November 2021 at 18:25:06 UTC nwi... at berkeley.edu wrote:
>
> It is a large band gap (TiO2), but with a has a shallow defect state,
> making the overall band gap small (~0.13eV).
>
> I know OT works better the wider the gap, but I had hooped that after the
> first SCF, it would still speed up quite a bit for the subsequent
> relaxation steps.
>
> I was trying to use FULL_KINETIC because
> IRAC+Rotations+occupation_preeconditioner together require that. This has
> the advantage of making defect states more robust by allowing for
> fractional occupations, but of course it can severely compromise
> convergence speed.
>
> When I switch to FULL_SINGLE_INVERSE preconditioner. I can grep and get:
>
> * outer SCF loop converged in* 3 iterations or 104 steps
>
> *outer SCF loop converged in* 2 iterations or 72 steps
>
> *outer SCF loop converged in* 3 iterations or 116 steps
>
> *outer SCF loop converged in* 2 iterations or 72 steps
>
> *outer SCF loop converged in* 2 iterations or 93 steps
>
> *outer SCF loop converged in* 2 iterations or 72 steps
>
> *outer SCF loop converged in* 2 iterations or 63 steps
>
> *outer SCF loop converged in* 2 iterations or 60 steps
>
>
> It doesn't look like its speeding up very much. I suppose 60 i better than
> 100, but its not what I expected.
> If this is just the way it is, then I'll live with it.
>
> On Wednesday, November 17, 2021 at 10:08:02 AM UTC-8 mattwa... at gmail.com
> wrote:
>
>> 'so for wide gap insulators you should for sure only need a few SCF
>> cycles to converge'
>> I meant to write when fairly relaxed / close to the minimum ...
>>
>>
>>
>> On Wednesday, 17 November 2021 at 18:06:33 UTC Matt Watkins wrote:
>>
>>> Well, CP2K was setup to do Born-Oppenheimer MD for bio systems - so
>>> for wide gap insulators you should for sure only need a few SCF cycles to
>>> converge.
>>>
>>> Is your system insulating (band gap, let's say > 0.2 eV)? If not
>>> different approach needed.
>>>
>>> If so, improve the OT setup - especially the preconditioner
>>>
>>> remove
>>> PRECONDITIONER FULL_KINETIC
>>> ENERGY_GAP 0.01
>>>
>>> try
>>>
>>> PRECONDITIONER FULL_SINGLE_INVERSE
>>>
>>> or (can be expensive for larger systems)
>>>
>>> PRECONDITIONER FULL_ALL
>>>
>>> and leave out the energy_gap (if you are using an up-to-date cp2k)
>>>
>>> Also check that you XC setup is correct ...
>>>
>>> Matt
>>>
>>>
>>> On Tuesday, 16 November 2021 at 17:58:59 UTC nwi... at berkeley.edu wrote:
>>>
>>>> Hello all,
>>>>
>>>> When I run a relaxation for a complex system, e.g. in my case a
>>>> defective transition metal oxide with hybrid dft on a modest ~200 atom
>>>> supercell, each SCF still takes quite a long time to converge.
>>>>
>>>> I originally came from vasp before switching to cp2k, and it in that
>>>> code, my experience was that once the first scf loop converged, the next
>>>> relaxation step would take much less time, and so on until the last few
>>>> steps converged in just a few iterations. This isn't my experience with
>>>> CP2K though. Running CG on my most recent relaxation I still find that
>>>> after more than 20 relaxation steps, 40-50 scf steps are required to
>>>> achieve convergence.
>>>>
>>>> Is this something that I could improve by changing certain settings?
>>>> Below is the relevant info for my input file. Please note that I understand
>>>> FULL_KINETIC and CG might lead to slower convergence than FULL_ALL + DIIS,
>>>> but my question lies in why convergence is not appreciably speeding up
>>>> rather than its absolute speed.
>>>>
>>>> -Nick
>>>>
>>>> &DFT
>>>>
>>>> BASIS_SET_FILE_NAME BASIS_MOLOPT
>>>>
>>>> BASIS_SET_FILE_NAME BASIS_MOLOPT_UCL
>>>>
>>>> BASIS_SET_FILE_NAME BASIS_ADMM
>>>>
>>>> BASIS_SET_FILE_NAME BASIS_ADMM_MOLOPT
>>>>
>>>> POTENTIAL_FILE_NAME GTH_POTENTIALS
>>>>
>>>> UKS T
>>>>
>>>> MULTIPLICITY 0
>>>>
>>>> CHARGE 4
>>>>
>>>> &SCF
>>>>
>>>> MAX_ITER_LUMO 400
>>>>
>>>> MAX_SCF 50
>>>>
>>>> EPS_SCF 1e-06
>>>>
>>>> SCF_GUESS RESTART
>>>>
>>>> &OT
>>>>
>>>> ALGORITHM STRICT
>>>>
>>>> MINIMIZER CG
>>>>
>>>> LINESEARCH 2PNT
>>>>
>>>> PRECONDITIONER FULL_KINETIC
>>>>
>>>> ENERGY_GAP 0.01
>>>>
>>>> ROTATION F
>>>>
>>>> OCCUPATION_PRECONDITIONER F
>>>>
>>>> &END OT
>>>>
>>>> &OUTER_SCF
>>>>
>>>> EPS_SCF 1e-06
>>>>
>>>> MAX_SCF 20
>>>>
>>>> &END OUTER_SCF
>>>>
>>>> &END SCF
>>>>
>>>> &AUXILIARY_DENSITY_MATRIX_METHOD
>>>>
>>>> ADMM_PURIFICATION_METHOD None
>>>>
>>>> METHOD BASIS_PROJECTION
>>>>
>>>> &END AUXILIARY_DENSITY_MATRIX_METHOD
>>>>
>>>> &QS
>>>>
>>>> EPS_DEFAULT 1e-12
>>>>
>>>> EPS_PGF_ORB 1e-16
>>>>
>>>> EXTRAPOLATION PS
>>>>
>>>> METHOD GPW
>>>>
>>>> &END QS
>>>>
>>>> &MGRID
>>>>
>>>> NGRIDS 5
>>>>
>>>> CUTOFF 550.0
>>>>
>>>> REL_CUTOFF 50.0
>>>>
>>>> &END MGRID
>>>>
>>>> &XC
>>>>
>>>> &XC_FUNCTIONAL NO_SHORTCUT
>>>>
>>>> &PBE
>>>>
>>>> SCALE_X 0.0
>>>>
>>>> SCALE_C 1.0
>>>>
>>>> &END PBE
>>>>
>>>> &XWPBE
>>>>
>>>> SCALE_X 0.063
>>>>
>>>> SCALE_X0 0.877
>>>>
>>>> OMEGA 0.07
>>>>
>>>> &END XWPBE
>>>>
>>>> &PBE_HOLE_T_C_LR
>>>>
>>>> SCALE_X 0.123
>>>>
>>>> CUTOFF_RADIUS 5.930000000000001
>>>>
>>>> &END PBE_HOLE_T_C_LR
>>>>
>>>> &END XC_FUNCTIONAL
>>>>
>>>> &HF
>>>>
>>>> FRACTION 1.0
>>>>
>>>> &SCREENING
>>>>
>>>> EPS_SCHWARZ 1e-07
>>>>
>>>> EPS_SCHWARZ_FORCES 1e-06
>>>>
>>>> SCREEN_P_FORCES T
>>>>
>>>> SCREEN_ON_INITIAL_P T
>>>>
>>>> &END SCREENING
>>>>
>>>> &INTERACTION_POTENTIAL
>>>>
>>>> POTENTIAL_TYPE MIX_CL_TRUNC
>>>>
>>>> OMEGA 0.07
>>>>
>>>> SCALE_COULOMB 0.06
>>>>
>>>> SCALE_LONGRANGE 0.063
>>>>
>>>> CUTOFF_RADIUS 5.930000000000001
>>>>
>>>> T_C_G_DATA t_c_g.dat
>>>>
>>>> &END INTERACTION_POTENTIAL
>>>>
>>>> &LOAD_BALANCE
>>>>
>>>> RANDOMIZE T
>>>>
>>>> &END LOAD_BALANCE
>>>>
>>>> &MEMORY
>>>>
>>>> EPS_STORAGE_SCALING 0.1
>>>>
>>>> MAX_MEMORY 2000
>>>>
>>>> &END MEMORY
>>>>
>>>> &END HF
>>>>
>>>> &END XC
>>>>
>>>> &END DFT
>>>>
>>>
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