Hi Elliot, Indeed, standard DFT-D2 does overestimate adsorption on metals, but a modified DFT-D2 version that I published doesn’t ;)
http://www.hindawi.com/journals/jtc/2013/327839/ <http://www.hindawi.com/journals/jtc/2013/327839/> I haven’t tried adsorption onto Ni surfaces specifically, but bulk Ni properties came out fine and adsorption on quite a few other metals (including Pt, Au, etc) gives quite reasonable results. In fact, it would be quite interesting for me to see if adsorption on Ni behaves as well as other surfaces, so by all means, try it out. I don’t use the vdw functionals in my research and have only read up on their progress briefly, but as far as I understood, they were not able to handle spin polarised systems initially, like Ni. Can anyone enlighten me on the status of vdw functionals for spin polarised calculations? Cheers, ———————————————————————— Martin P. Andersson Associate Professor Nano-Science Center, Department of Chemistry University of Copenhagen, Denmark Tel: +45 3532 0280 Mobile: +46 733 893091 E-mail: [email protected] ———————————————————————— > On 03 May 2016, at 10:26, Giuseppe Mattioli <[email protected]> > wrote: > > > Dear Elliot > I do not know if I understand well your questions, but I try to answer: > >> Could someone please assist me as to how to account for London >> dispersion forces with QE or essentially how to do a DFT-D2 calculation >> with the the aim of accounting for the energy contribution of dispersion >> forces. > > Use vdw_corr='grimme-d2' > You will find in the output the dispersion force contribution to the total > energy: > > ! total energy = -2369.89004091 Ry > Harris-Foulkes estimate = -2369.89004090 Ry > estimated scf accuracy < 0.00000001 Ry > > The total energy is the sum of the following terms: > > one-electron contribution = -22567.16723495 Ry > hartree contribution = 11423.49753189 Ry > xc contribution = -757.02966668 Ry > ewald contribution = 9530.66102736 Ry > Dispersion Correction = -0.98373910 Ry > Hubbard energy = 1.13399751 Ry > smearing contrib. (-TS) = -0.00195694 Ry > >> I'm trying to account for the energy contribution of London dispersion >> forces on the total energy of a hydrazine-nickel system. > > Remember that DFT-D2 badly overestimate the interaction of molecules with > metal surfaces, see Grimme, S.; Antony, J.; Ehrlich, S.; Krieg, H. A > consistent and accurate ab initio parametrization of density functional > dispersion correction (DFT-D) for the 94 elements H-Pu. J. Chem. Phys. 2010, > 132, 154104. In cases such as N2H2 on Ni I would rather use vdwdf or > vdwdf-c09 (see usage and related papers in QE documentation). > >> ------------------------------ >> &CONTROL >> tefield = .TRUE., >> dipfield = .TRUE., >> disk_io = 'low', >> >> &SYSTEM >> edir=3, >> emaxpos=0.65, >> eopreg=0.06, >> eamp=0, >> ------------------------------ >> > > This is a well tested but old and complex machine to correct the interaction > of a dipole with its periodic replicas along z. I do not know if it is > possible to estimate its impact on dispersion forces in a different way than > by using/not using the dipole correction and check the difference between > the above "Dispersion Correction" contribution to the total energy. However, > I've satisfactorily used for a system similar to yours (thiol SAM on Au > surface) this new setup (again, read the documentation and related papers), > which decouple in a simpler way the dipole along z. > > &system > input_dft='vdw-df-c09' > assume_isolated = 'esm', > esm_bc='bc1', > / > > HTH > Giuseppe > > > On Tuesday, May 03, 2016 12:41:49 AM Elliot Menkah wrote: >> Hi all, >> I'm trying to account for the energy contribution of London dispersion >> forces on the total energy of a hydrazine-nickel system. >> >> Could someone please assist me as to how to account for London >> dispersion forces with QE or essentially how to do a DFT-D2 calculation >> with the the aim of accounting for the energy contribution of dispersion >> forces. >> >> When I correct the net-surface dipole on a system by using the variables >> and values below, does it affect the energy from dispersion forces, if >> so, how? >> How does correcting the net-surface dipole relate to accounting for >> dispersion forces? >> >> ------------------------------ >> &CONTROL >> tefield = .TRUE., >> dipfield = .TRUE., >> disk_io = 'low', >> >> &SYSTEM >> edir=3, >> emaxpos=0.65, >> eopreg=0.06, >> eamp=0, >> ------------------------------ >> >> >> I'm basically trying to account for London dispersion forces on a >> hydrazine-nickel system. >> Any info to help my computation would be gladly appreciated. >> Thank you >> >> Kind Regards, >> Elliot > > ******************************************************** > - Article premier - Les hommes naissent et demeurent > libres et égaux en droits. Les distinctions sociales > ne peuvent être fondées que sur l'utilité commune > - Article 2 - Le but de toute association politique > est la conservation des droits naturels et > imprescriptibles de l'homme. Ces droits sont la liberté, > la propriété, la sûreté et la résistance à l'oppression. > ******************************************************** > > Giuseppe Mattioli > CNR - ISTITUTO DI STRUTTURA DELLA MATERIA > v. Salaria Km 29,300 - C.P. 10 > I 00015 - Monterotondo Stazione (RM), Italy > Tel + 39 06 90672836 - Fax +39 06 90672316 > E-mail: <[email protected] <mailto:[email protected]>> > http://www.ism.cnr.it/en/staff/giuseppe-mattioli/ > <http://www.ism.cnr.it/en/staff/giuseppe-mattioli/> > ResearcherID: F-6308-2012 > > _______________________________________________ > Pw_forum mailing list > [email protected] <mailto:[email protected]> > http://pwscf.org/mailman/listinfo/pw_forum > <http://pwscf.org/mailman/listinfo/pw_forum>
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