Van der waal interaction calculation

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naresh124 · #1 Post by **naresh124** » Tue Sep 11, 2012 9:50 am

I have doubts in following questions
I am doing calculation for a system which contains C and Pt atoms,
To use tag LVDW =.TRUE., VDW_C6 and VDW_R0 parameters are required. But i found that
these parameters are given for only C atoms not Pt. How can i find VDW_C6 and VDW_R0
parameters for Pt.

#2 Post by **admin** » Wed Sep 12, 2012 11:05 am

Parameters of the DFT-D2 method are developed only for first five lines of the periodic table (until Xe). For atoms behind Xe, like e.g. Pt, one can input parameters via INCAR, if they are available. Parameters for Pt were released for program packages like Gaussian. If you need to use them in VASP contact directly parameters developer Stefan Grimme.

naresh124 · #3 Post by **naresh124** » Wed Sep 12, 2012 12:01 pm

Thanks for your reply, If i use tag LUSE_VDW = .TRUE. (vdW-DF) for van der waal interactions, what other tags and parameters are required for INCAR file.
Does vdW-DF works for Pt? if it works ,how can i implement in vasp

kelum · #4 Post by **kelum** » Wed Sep 12, 2012 4:29 pm

vdW-DF is in VASP, the 'performance' depends on what version you want to use.
The Dion et al version (vdW-DF) and the Lee at al version (vdW-DF2) will
give way too large lattice constants for Pt. See the paper by Wellendorf
http://www.springerlink.com/content/c80 ... lltext.pdf
and/or our paper (we don't have Pt but the trends are similar across the 5th and 6th rows)
http://prb.aps.org/abstract/PRB/v83/i19/e195131
The optB88-vdW is close to PBE for the lattices, which is good enough.
How to set these functionals is documented in the manual
(for example, to get optB88-vdW, set LUSE_vdW=.TRUE.; AGGAC=0.00;
GGA=BO; PARAM1 = 0.1833333333; PARAM2 = 0.2200000000 and the
kernel file in your working directory).

Since you have a carbon in your simulation you might also want to check this paper
http://th.fhi-berlin.mpg.de/site/upload ... 6-2012.pdf
which looks at benzene on Pt and other metals and compares different vdW-DF versions as well.