[Q-e-developers] B3LYP in QE
Andrea Ferretti
andrea.ferretti at nano.cnr.it
Tue Nov 3 19:50:56 CET 2015
Hi Satomichi,
thanks for pointing this out.
I went for VWN-1-RPA for consistency with NWchem and libxc (also
interfaced with QE). A different vwn choice would not be difficult at all
to be implemented at this stage (when we are changing/fixing the
functional definitio), especially if considered more standard...
In any case, I would try to make a choice now, in order not to keep on
changing the definition of the functional.
Andrea
>
> I am developing both Gaussian basis-set software and plane-wave software,
> thus, I am more or less familiar with B3LYP.
> Let me explain VWN functionals in B3LYP.
>
> The original B3LYP is defined with VWN-5 (A.D.Becke, J. Chem. Phys., 107, 8554 (1997)).
> And almost all of quantum chemical softwares (with Gaussian basis-set) adopt VWN-5.
> However, some softwares use other VWNs.
> For examples, Gaussian09 uses VWN-3, NWChem uses VWN-1-RPA.
>
> If you want to implement Becke’s 3-parameter formulation,
> I recommend to adopt VWN-5 or some VWNs can be selected.
>
> Regards,
> Satomichi
>
>
> 差出人: Andrea Ferretti
> 送信日時: 2015年11月3日 火曜日 8:26
> 宛先: General discussion list for Quantum ESPRESSO developers
>
>
>
> Dear all,
>
> these days I've addressed a problem that I have been facing for some time,
> i.e. the validation of B3LYP results obtained by QE.
> Basically, comparing the restuls of hybrid calculations done with QE (say
> for a molecule) with other quantum chemistry (localized basis set) codes I
> was able to get very a good agreement on the results (mostly eigenvalues)
> for HF and PBE0 (besieds LDA, PBE, etc), but not as good for B3LYP.
>
> To be more precise, I have looked at small molecules based on light
> elements (such Cl2, CH4, benzene, etc), and compared with MOLPRO,
> NWchem, and, to a smaller extent, Gaussian and ORCA (courtesy of Daniele
> Varsano).
>
> Common experience was that, when using a rather large basis set (such as
> aug-cc-pTVZ), the agreement of eigenvalues compared to pp-plane-waves
> reached few tens of meV (from 0.01 to 0.05 eV in the worst cases, at
> least for frontier orbitals). This worked across several functionals
> (local, semilocal, hybrids but B3LYP)
> Some numbers are listed below.
>
> All in all, this analysis pointed out a problem localized in the
> B3LYP.
> Indeed, looking into the implementation I think that I've found at least a
> couple of differences wrt the reference paper
>
> P.J. Stephens,F.J. Devlin,C.F. Chabalowski,M.J. Frisch,
> J.Phys.Chem 98, 11623 (1994)
> see Eq. (2)
>
> as well as the implementations of NWchem and libxc.
>
> Basically:
>
> * QE implements vwn lda-correlation according to vwn-1
> of the vwn paper,
> S.H.Vosko, L.Wilk, M.Nusair, Can.J.Phys. 58,1200(1980)
> while vwn-1-rpa has to be used for b3lyp
>
> * the vwn-1-rpa contribution has to be included with a proper
> scaling factor and summed to the LYP correlation (both
> icorr and igcc)
>
> after these changes have been implemented, the agreement of the QE-b3lyp
> results with other reference data is much better (of the same order of
> PBE0 or alike).
>
> In doing so I've also implemented X3LYP, according to the ref:
> X. Xu, W.A Goddard III, PNAS 101, 2673 (2004).
>
> Results are also reported and in the same quantitative agreement with
> localized basis set codes found for other functionals.
>
> =========
>
> In the attachment you can find a tgz file with a patch to few QE files
> implementing the xc-functionals.
>
> So far I have not done any commit to the trunk, since I wanted to first
> hear any comments/suggestions.
>
> What do you think ?
>
> take care
> Andrea
>
> =========
>
> Cl2 molecule
> #========================================================
> # NWCHEM results, AVTZ basis
> #========================================================
> HOMO [eV] LUMO [eV] lowest eig [eV]
> LDA -7.48 -4.65 -23.39
> VWN-RPA -7.9572 -5.1218 -23.8799
> PBE -7.36 -4.44 -23.33
> PBE0 -8.79 -3.36 -26.02
> HF -12.16 +0.51 -32.98
>
> X3LYP -8.5772 -3.5198 -25.5847
> B3LYP -8.52 -3.63 -25.44
>
> #========================================================
> # QE, plane-waves (this work)
> #========================================================
> HOMO [eV] LUMO [eV] lowest eig [eV]
> LDA -7.45 -4.66 -23.60
> VWN-RPA -7.9332 -5.1423 -24.0844
> PBE -7.39 -4.54 -23.52
> PBE0 -8.82 -3.49 -26.18
> HF -12.27 >0 -33.11
>
> X3LYP -8.6243 -3.6022 -25.7891
>
> B3LYP (FIX) -8.58 -3.72 -25.65
> B3LYP (WRONG) -8.88 -4.03 -25.96
>
> ===========
>
> CH4 molecule
> #========================================================
> # NWCHEM results, AVTZ basis
> #========================================================
> HOMO [eV] LUMO [eV] lowest eig [eV]
> LDA -9.4622 -3.2760 -16.9573
> PBE -9.4413 -3.6852 -17.0532
> PBE0 -10.9809 +0.0368 -19.4375
> HF -14.8200 +0.8104 -25.6458
>
> X3LYP -10.8204 -0.1998 -19.0752
> B3LYP -10.7594 -0.2262 -18.9560
>
>
> #========================================================
> # QE, plane-waves (this work)
> #========================================================
> HOMO [eV] LUMO [eV] lowest eig [eV]
> LDA -9.4896 -0.5150 -16.9666
> PBE -9.4829 -0.5322 -16.9490
> PBE0 -11.0220 -0.2528 -19.3512
> HF -14.8492 0.1920 -25.6397
>
> X3LYP -10.8440 -0.3028 -19.0213
>
> B3LYP (FIX) -10.7898 -0.3041 -18.9041
> B3LYP (WRONG) -11.1000 -0.4030 -19.2163
>
>
>
> --
> Andrea Ferretti, PhD
> S3 Center, Istituto Nanoscienze, CNR
> via Campi 213/A, 41125, Modena, Italy
> Tel: +39 059 2055322; Skype: andrea_ferretti
> URL: http://www.nano.cnr.it
>
>
--
Andrea Ferretti, PhD
S3 Center, Istituto Nanoscienze, CNR
via Campi 213/A, 41125, Modena, Italy
Tel: +39 059 2055322; Skype: andrea_ferretti
URL: http://www.nano.cnr.it
More information about the developers
mailing list