Finding the binding energy and distance for diamond


I am a getting use to using LAMMPS and as a way to learn it I am trying to simulate something with very well known information. This being calculating the binding energy and distance for diamond. I am having some issues currently. My energy gives me zero and I am having an issue with being able to compute any bond distance and display it. Any help would be much appreciated.

The Code:

Initialize simulation

units metal

dimension 3

boundary p p p

atom_style full

Create the atoms

lattice diamond 3.567 orient x 1 0 0 orient y 0 1 0 orient z 0 0 1

region box block 0 1 0 1 0 1 units lattice

create_box 1 box

create_atoms 1 box

mass 1 12.0107

bond_style morse

Define the potential

pair_style tersoff

pair_coeff * * SiC.tersoff C

neighbor 0.1 bin

neigh_modify delay 10 check yes

Define Computations

compute bleng all bond/local dist

compute eng all bond/local engpot

Minimize energy

reset_timestep 0

thermo 10

thermo_style custom step ebond

min_style cg

minimize 1e-25 1e-25 5000 10000

Define Variables

variable bondeng equal “ebond”

variable bondleng equal “bleng”

Print values

print “Bond length (Angstroms) = ${bondleng};”

print “Bond Energy (eV) = ${bondeng};”

print “This ran!”

Thank you,

Philip Chrostoski

PhD Candidate

Department of Physics and Astronomy

Center for Nanoscience

University of Missouri - St. Louis

The bond/local command works for permanent bonds defined
by a data file and models setup by the bond_style command.

Tersoff (and other bond-order potentials) do not define permanent bonds.
Useful commands might be:

compute pair/local = pairwise distances
compute rdf = distribution of pairwise distances
compute coord/atom = coordination # of each atom