[CP2K:7089] SCF loop can not converge with using hybrid functional

S Ling lingsa... at gmail.com
Wed Oct 28 01:18:00 CET 2015


Hi

It's always good to start your hybrid-DFT calculation from a pre-converged
GGA wavefunction and a GGA optimised geometry. This will likely to
accelerate your SCF convergence of hybrid-DFT calculation, or if you are
running a GEO_OPT, then it will take less steps for the GEO_OPT to converge
at hybrid-DFT level.

In terms of accelerating the SCF convergence of metals, another possibility
is to increase the electronic temperature for smearing. I am not sure how
will this affect your target property. Maybe some other people can give you
more suggestions on that.

An additional suggestion: you would like to use the PBE0+D3 functional,
then in the &VDW_POTENTIAL section, you should change the
REFERENCE_FUNCTIONAL from PBE to PBE0. The D3 vdW correction contains
several parameters which are XC-dependent.

SL



On 27 October 2015 at 23:57, jiabo <lejia... at 163.com> wrote:

> Thanks for the reply. I have attached the input and output files below. I
> do not use a pre-converged wavefunction in this calculation.
>
> Bests,
> Jiabo
>
>
>
> On Tuesday, 27 October 2015 21:35:14 UTC, S Ling wrote:
>>
>> Hi
>>
>> Can you upload the full input and output? And did you start from a
>> pre-converged PBE wavefunction?
>>
>> SL
>> On 27 Oct 2015 21:07, "jiabo" <leji... at 163.com> wrote:
>>
>>> Hi, every cp2k user
>>>
>>> I am trying to use a hybrid functional (PBE0) to calculate a
>>> metallic/water system, only single point energy needed. However, I find the
>>> the SCF loop can not converge, even after 200 steps. Does anyone know how
>>> to adjust the parameter to make the SCF converge faster? Is that helpful to
>>> set up a bigger CUTOFF_RADIUS value in the input below?
>>>
>>> Best regards,
>>> Jiabo
>>>
>>>    &XC
>>>      &XC_FUNCTIONAL
>>>         &PBE
>>>           SCALE_X 0.75
>>>           SCALE_C 1.0
>>>         &END
>>>         &PBE_HOLE_T_C_LR
>>>           CUTOFF_RADIUS 2.0
>>>           SCALE_X 0.25
>>>         &END
>>>       &END XC_FUNCTIONAL
>>>       &HF
>>>         &SCREENING
>>>           EPS_SCHWARZ 1.0E-7
>>>           SCREEN_ON_INITIAL_P FALSE
>>>         &END
>>>         &MEMORY
>>>           MAX_MEMORY 10000
>>>           EPS_STORAGE_SCALING 0.1
>>>         &END
>>>         &PERIODIC
>>>           NUMBER_OF_SHELLS  0
>>>         &END
>>>         &INTERACTION_POTENTIAL
>>>           POTENTIAL_TYPE TRUNCATED
>>>           CUTOFF_RADIUS 2.0
>>>           T_C_G_DATA ./t_c_g.dat
>>>         &END
>>>         FRACTION 0.25
>>>       &END
>>>
>>>
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