# [CP2K-user] [CP2K:11654] Re: Range Separated hybrid XC

Zdenek Futera fute... at gmail.com
Thu May 2 15:45:45 UTC 2019

Dear Simone,

To get the general 1/r = (a+b erf(mu*r))/r + (1 - (a+b erf(mu*r)))/r operator splitting you need to specify

&XC_FUNCTIONAL no_shortcut

&PBE

PARAMETRIZATION orig

SCALE_C 1.0

SCALE_X 1-a-b

&END PBE

&XWPBE

OMEGA mu

SCALE_X b

SCALE_X0 0.0

&END XWPBE

&END XC_FUNCTIONAL

&HF

&INTERACTION_POTENTIAL

POTENTIAL_TYPE mix_cl

OMEGA mu

SCALE_COULOMB a

SCALE_LONGRANGE b

&END INTERACTION_POTENTIAL

&END HF

Regards,

Zdenek

From: <cp... at googlegroups.com> on behalf of Simone Piccinin <piccini... at gmail.com>
Date: Thursday, 2 May 2019 at 16:35
Subject: [CP2K:11654] Re: Range Separated hybrid XC

Dear All,

I’m interested in performing a calculation with range separated hybrid functionals, where the 1/r operator is written in the general form 1/r = {1-[a+b*erf(mu*r)]}/r + [a+b*erf(mu*r)]/r.

I had a look at the description of the keywords and I think one can do this with the following setting:

&INTERACTION_POTENTIAL

POTENTIAL_TYPE MIX_CL

SCALE_COULOMB a

SCALE_LONGRANGE b

&END

FRACTION 1.0

One can recover the HSE functional with a=-b=0.25 and u=0.11, and indeed I could reproduce the HSE total energy of the example regtest-hybrid-3/CH3-hybrid-HSE06-lsd.inp replacing POTENTIAL_TYPE SHORTRANGE with MIX_CL and using the above input parameters.

I’m not sure, however, how to modify this section of the HSE potential for the generic case:

&XWPBE

SCALE_X -0.25

SCALE_X0 1.0

&END

&PBE

SCALE_X 0.0

SCALE_C 1.0

&END PBE

&END XC_FUNCTIONAL

How do I express SCALE_X, SCALE_X0 in &XWPBE and SCALE_X in &PBE in terms of a and b?

Thanks!

Simone Piccinin

CNR-IOM, Trieste

On Wednesday, November 21, 2018 at 1:03:09 PM UTC+1, Andres Ortega wrote:

Dear CP2K users,

I was wondering if you could help me with a doubt? I am curious about something to try on CP2K

Is it possible to use an RSH exchange-correlation functional in cp2k?

It will be equivalent to use an HSE06 functional with the difference now I can use also LR for PBE?

Will it follow for example the same shape as the ones introduced in NWChem?

Andres O.

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