Dear Colleagues,

We are developing a discrete-to-continuum procedure that will allow to model a graphene bilayer as a continuum sheet. We are able to compare continuum and discrete simulations results for fake simple systems (e.g., in-plane harmonic extensional, torsional, and dihedral springs + LJ or kolmogorov/crespi/z interactions between the layers) at zero temperature and the results look pretty good. The next step is to increase the degree of complexity; to this end we would like to investigate the kolmogorov/crespi/full potential, while for the moment continuing to use harmonic potentials to model other interactions. Even though the code below works for kc/z, the obvious modifications that I attempted to adjust these files for kc/full do not seem to work. My questions are:

(1) Is there anything in the kc/full potential that would prevent it from working with harmonic potentials in place of tersoff or airebo?

(2) If not, what modifications need to be made to the files below to make them agreeable to LAMMPS?

Note that, at this point, I do not need simulations to result in anything physically realistic hence the numbers I am using are bogus.

Many thanks in advance for your help.

Dmitry

-------------- in.graphene-----------

dimension 3

boundary s s s

atom_style full

neighbor 0.3 bin

neigh_modify delay 5

read_data generate_initial/initial_data.txt

mass * 1.0

# Potentials

pair_style hybrid/overlay kolmogorov/crespi/z 12.0

pair_coeff * * none

pair_coeff 1*2 1*2 kolmogorov/crespi/z CC.KC C C

bond_style harmonic

bond_coeff * 5.E-1 1.42

angle_style harmonic

angle_coeff * 3.625E-2 120

dihedral_style harmonic

dihedral_coeff * 2.52E-2 -1 2

# define groups

group lower type 2

group mobile type 1

# initial velocities

compute new mobile temp

velocity mobile zero linear

fix 1 mobile nvt temp 1E-3 1E-3 1E-3

fix 2 lower setforce 0.0 0.0 0.0

fix 3 mobile viscous 0.1

#fix 3 all temp/rescale 100 0.1 0.1 0.01 1.0

timestep 0.003

thermo 1000

thermo_modify temp new

dump 1 mobile xyz 1000 graphene.xyz

dump 2 lower xyz 1000 substrate.xyz

run 1000000

print “Simulation complete”

--------------CC.KC----------

# Kolmogorov-Crespi Potential

# Cite as A.N. Kolmogorov & V. H. Crespi,

# Registry-dependent interlayer potential for graphitic systems

# Physical Review B 71, 235415 (2005)

# z0 C0 C2 C4 C delta lambda A S

C C 3.34 15.071 12.029 4.0933 3.0030 0.578 3.629 10.238 1.0