[CP2K-user] Range Separated hybrid XC

[Simone Piccinin]

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?
>
> Thank you for your time 
>
> Andres O.
>
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