[Pw_forum] rVV10 vdW functionals

[Giuseppe Mattioli]

Dear Sam
This I've found in the original VV10 paper
Oleg A. Vydrov and Troy Van Voorhis
THE JOURNAL OF CHEMICAL PHYSICS 133, 244103 (2010)

"In the rest of this article we will consider one
particularly apt combination of the exchange and correlation
terms,

E_xc^[VV10] = E_x rPW86 + E_c PBE + E_c VV10 (27)

where E c PBE is the semilocal correlation energy functional in
the generalized gradient approximation of Perdew, Burke, and
Ernzerhof (PBE). 23 Hereafter, we will often refer to the XC
functional of Eq. (27) simply as VV10."

A few lines below it is stated

"The full XC energy in vdW-DF2 is defined as

E_xc^[vdW-DF2] = E_x rPW86 + E_c LDA + E_c-nl vdW-DF2 (28)

where E_c LDA is the correlation energy in the local density
approximation, for which we use the parameterization of
Perdew and Wang."

This might be the source of some confusion arising in the following  
papers, all comparing VV10 or rVV10 with other vdw-df approaches.

HTH

Giuseppe


Quoting "Azadi, Sam" <s.azadi at imperial.ac.uk>:

> my question is that according to the paper there is no gradient  
> correction on correlation (pbc) in the rVV10 functional,
> while based on the functional.f90 module file the ‘pbc' is included  
> in the rVV10 .
>
> Yours,
> Sam Azadi
> —————
> Imperial College London
> On 17 Oct 2017, at 14:17, Jess Wellendorff  
> <jess.wellendorff at quantumwise.com<mailto:jess.wellendorff at quantumwise.com>>  
> wrote:
>
> sla: Slater LDA exchange
> pw: PerdewWang LDA correlation
> rpw86: rPW86 exchange
> pbc: PBE correlation
> vv10: VV10 nonlocal correlation
>
> so GGA correlation is included by "pbc".
>
> Cheers,
> Jess Wellendorff
>
> On 10/17/2017 03:11 PM, Azadi, Sam wrote:
> Dear QE community,
>
> According to page two last paragraph of second column of:
>
>  R. Sabatini, T. Gorni, and S. de Gironcoli, Phys. Rev. B 87,  
> 041108(R) (2013).
>
> the full vdW-rVV10 XC functional is defined as:
>
> whereas according to line 128 Modules/funct.f90 of QE6.1 :  "rvv10"  
> = "sla+pw+rw86+pbc+vv10"     = rVV10
>
> is there any gradient correction on correlation (pbc) in vdW-rVV10?
>
> Thanks,
> Sam Azadi
> -----
> Imperial College London
>
>
>
>
>
>
>
>
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> --
> Jess Wellendorff
> Senior Applications Engineer
> Synopsys QuantumWise
> Copenhagen, Denmark
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GIUSEPPE MATTIOLI
CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
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