LennardJones

The Lennard-Jones potential models both attractive and repulsive forces between particles. It’s commonly used for modeling non specific interactions between particles.

There are three types of Lennard-Jones potentials implemented:

LennardJonesType1

\[U = 4\epsilon \left[ \left(\frac{\sigma}{r}\right)^{12} - \left(\frac{\sigma}{r}\right)^6 \right]\]

LennardJonesType2

\[U = \epsilon \left[ \left(\frac{\sigma}{r}\right)^{12} - 2\left(\frac{\sigma}{r}\right)^6 \right]\]

LennardJonesType3

\[U = \epsilon \left[ 5\left(\frac{\sigma}{r}\right)^{12} - 6\left(\frac{\sigma}{r}\right)^{10} \right]\]

For all types:

\(\epsilon\) is the depth of the potential well
\(\sigma\) is the distance at which the potential is zero
\(r\) is the distance between the particles

type: NonBonded, LennardJonesType1 (or LennardJonesType2 or LennardJonesType3)
parameters:
- cutOffFactor: real: Interaction range as a multiple of sigma
data:
- name_i: string: Type of the particle i
- name_j: string: Type of the particle j
- epsilon: real: Potential well depth \([energy]\)
- sigma : real: Zero-potential distance \([distance]\)

Example:

"lj":{
  "type":["NonBonded","LennardJonesType1"],
  "parameters":{
    "cutOffFactor":2.5,
    "condition":"all"
  },
  "labels":["name_i", "name_j", "epsilon", "sigma"],
  "data":[
    ["A", "A", 1.0, 1.0],
    ["A", "B", 1.2, 0.9],
    ["B", "B", 0.8, 1.1]
  ]
}

Note

For an explanation of how select the neighbors list (and the use of the condition parameter), see the common documentation for the non-bonded potentials.