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: <giuseppe.matti...@ism.cnr.it> http://www.ism.cnr.it/en/staff/giuseppe-mattioli/ ResearcherID: F-6308-2012 _______________________________________________ Pw_forum mailing list Pw_forum@pwscf.org http://pwscf.org/mailman/listinfo/pw_forum