[CP2K-user] [CP2K:16254] Re: Improve extrapolation between relaxation steps?
Nicholas Winner
nwinner at berkeley.edu
Wed Nov 17 18:25:06 UTC 2021
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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