[Pw_forum] London Dispersion force: DFT-D2
Giuseppe Mattioli
giuseppe.mattioli at ism.cnr.it
Tue May 3 10:26:25 CEST 2016
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
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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.mattioli at ism.cnr.it>
http://www.ism.cnr.it/en/staff/giuseppe-mattioli/
ResearcherID: F-6308-2012
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