Platinum-Graphene interaction

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1

Dear Lammps users,

I am trying to simulate Platinum-Graphene interaction using Pt-C Albe tersoff potential. I want to calculate the Adsorption Energy of Pt/Carbon system. Surprisingly The Energy of Pt/Graphene system is bigger than of Energy of Platinum plus Energy of Graphene !!!

At first I minimize Platinum in vaccum ,then minimize graphene, and then put the minimized structure of Platinum on top of Graphene ( in cut-off distance) and minimize the whole structure.

Here is the main part of my input script:

boundary p p s
read_data pt-cnt-mini.data

pair_style tersoff
pair_coeff * * PtC.tersoff C Pt

compute eng all pe/atom
compute eatoms all reduce sum c_eng

dump 1 all custom 500 dump.Pt-G-bond id type x y z vx vy vz fx fy fz c_eng

min_style cg
minimize 1e-10 1e-10 10000 1000

Version of Lammps is LAMMPS (28 Jun 2016).

Do you have any idea why The energy of Pt/graphene is bigger than energy of Pt + energy of Graphene ? In the literature it is less.

Thank you in advance,

Samaneh

2

I don’t know the answer to your Q. But it is doubtful
that it is a LAMMPS issue (e.g. bug). LAMMPS
is just minimizing based on what is in your
potential file for Tersoff C and Pt. Those cross
interactions should be driving the relaxed energy
of your hybrid system. You could probably setup
a simple system (e.g. 2 atoms of C, 2 of Pt) and
see what happens to the energy when you change
C -> Pt or vice versa. Do it first w/out minimization
and see if the energy changes are what you expect.

Steve