SurfaceGeneralLennardJones

The SurfaceGeneralLennardJones potential is a flexible surface interaction that combines properties of both the Lennard-Jones and WCA potentials. It allows for both attractive and purely repulsive interactions based on the sign of the epsilon parameter.

There are two types of SurfaceGeneralLennardJones potentials implemented:

SurfaceGeneralLennardJonesType1

\[\begin{split}U(z) = \begin{cases} WCA_{Type1}(z-z_s; \epsilon, \sigma) & \text{if } \epsilon > 0 \\ LJ_{Type1}(z-z_s; |\epsilon|, \sigma) & \text{if } \epsilon < 0 \end{cases}\end{split}\]

SurfaceGeneralLennardJonesType2

\[\begin{split}U(z) = \begin{cases} WCA_{Type2}(z-z_s; \epsilon, \sigma) & \text{if } \epsilon > 0 \\ LJ_{Type2}(z-z_s; |\epsilon|, \sigma) & \text{if } \epsilon < 0 \end{cases}\end{split}\]

where \(WCA\) and \(LJ\) refer to the respective WCA and Lennard-Jones potentials defined in the SurfaceWCA and SurfaceLennardJones sections.

type: Surface, SurfaceGeneralLennardJonesType1 or SurfaceGeneralLennardJonesType2
parameters:
- surfacePosition: real: Position of the surface along the z-axis \([distance]\)
data:
- name: string: Name of the particle type
- epsilon: real: Energy scale of the interaction (sign determines attractive/repulsive nature) \([energy]\)
- sigma: real: Characteristic distance \([distance]\)

Example:

"surfaceGeneralLJ":{
  "type":["Surface","SurfaceGeneralLennardJonesType1"],
  "parameters":{
    "surfacePosition": 0.0
  },
  "labels":["name", "epsilon", "sigma"],
  "data":[
    ["A", 1.0, 1.0],
    ["B", -0.5, 0.8]
  ]
}

Note

The SurfaceGeneralLennardJones potential behaves like WCA for positive epsilon values and like Lennard-Jones for negative epsilon values.

Tip

This potential is versatile and can be used to model a wide range of surface interactions, from purely repulsive to strongly attractive, within a single simulation.