[Pw_forum] vdW+PBE0

[Giuseppe Mattioli]

Dear Valentina
I'm afraid that you can use the semiempirical Grimme's DFT-D2  
correction only. AFAIK open shell systems, like oxygen molecules (If I  
understand correctly your purpose), cannot be treated by using the  
present ab initio implementation of VDW-DF, and the new XDM and TSVDW  
implementations cannot (still) be used with EXX functionals.
If you are not going to perform open shell calculation instead, you  
can mess with the input_dft variable and add one of the long-range vdw  
terms to one of the EXX functionals. I did something of the kind some  
time ago (a HSE+VDW functional) which was apparently fine, but hic  
sunt leones...
HTH

Giuseppe

Giuseppe Mattioli
ISM-CNR
Italy

Quoting Paolo Giannozzi <paolo.giannozzi at uniud.it>:

> van der Waals with semi-empirical corrections a la Grimme
> and PBE0, yes; van der Waals with non-local functionals
> and PBE0 ... it should be possible: there is a complex
> mechanism for naming XC functionals that should allow to
> mix and match all functionals. Not sure that it makes
> sense, though, no warranty that it will actually work.
>
> P.
>
> On Thu, 2013-12-12 at 16:22 +0100, DELLACA' Valentina (CRF) wrote:
>> Dear Quantum Espresso users,
>>
>> We are modeling a system which needs the hybrid functional approach to
>> be correctly simulated. Next, we need to compute the Oxygen chemical
>> potential, and it has to be compared with the energy of the system. It
>> is a fact that van der Waals interactions are not negligible when
>> modeling molecular Oxygen.  In order to have comparable quantities, we
>> are wondering if it is possible to use in Quantum Espresso a mixture
>> of van der Waals and PBE0 to model the Oxygen molecule.
>>
>> Thanks,
>>
>> Valentina
>>
>>
>>
>>
>>
>> Valentina Dellacà
>> Group Materials Labs
>> PA&CT – Virtual Analysis & Materials Modelling
>>
>>
>> Centro Ricerche Fiat S.C.p.A.
>> Sede legale e amministrativa: Strada Torino, 50
>> 10043 Orbassano (TO), Italia
>> Tel  +39 011 9083138
>> Fax +39 011 9083666
>>
>> www.crf.it
>>
>>
>>
>>
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>
> --
>  Paolo Giannozzi, Dept. Chemistry&Physics&Environment,
>  Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
>  Phone +39-0432-558216, fax +39-0432-558222
>
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    Giuseppe Mattioli
    CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
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