# potfit wiki

open source force-matching

### Sidebar

User Guide

Examples

Potential Databases

More

examples:potentials:pair:6

# Examples : Pair Potentials

Warning: This is an example potential. Please do NOT use it for any real simulations!

This is a simple pair potential that can be used in potfit. The analytic function used is a Lennard-Jones.

It makes use of the invariant potentials feature.

Example_Pair_6
#F 0 3
#T PAIR
#I 1 0 0
#E

# This potential is invariant, it will not be optimized
type lj
cutoff 6.0
epsilon 0.10    0.00    1.00
sigma   2.50    1.00    4.00

type lj
cutoff 6.0
epsilon 0.10    0.00    1.00
sigma   2.50    1.00    4.00

type lj
cutoff 6.0
epsilon 0.10    0.00    1.00
sigma   2.50    1.00    4.00

The invariant potentials feature is the equivalent of the fixing a parameter, except it applies to an entire potential. In the example the first lj-potential will not be optimized. This is indicated in the #I header line. Each item therein corresponds to a potential. Setting the value to 1 disables the optimization.

### makeapot

The example potential can be generated with the following makeapot command:

Invariant potentials have to be set up manually in the potential file!

makeapot -n 2 -i pair -f 3*lj
examples/potentials/pair/6.txt · Last modified: 2018/01/10 17:37 by daniel