Interaction Potentials

CustomPotential

Implements a potential that evaluates a user defined function.

Expects values f, and p, which respecively are a callable and a list of parameters. The function should be called f(r::Number, p) and it should produce either a Number, in the case of a single-component system, or an SMatrix, in the case of a multicomponent system.

Example:

f = (r, p) -> 4*p[1]*((p[2]/r)^12 -  (p[2]/r)^6)
potential = CustomPotential(f, (1.0, 1.0))

HardSpheres

Implements the hard-sphere pair interaction for single component systems $ u(r) = \infty$ for $r < 1$ and $u(r) = 0$ for $r > 1$, or $u_{ij}(r) = \infty$ for $r < D_{ij}$ and $u_{ij}(r) = 0$ for $r > D_{ij}$ for mixtures.

For mixtures expects either a vector $D_i$ of diameters for each of the species in which case an additive mixing rule is used $\left(D_{ij} = (D_{i}+D_{j})/2\right)$ or a matrix $D_ij$ of pair diameters.

Example:

potential = HardSpheres(1.0)

Example:

potential = HardSpheres([0.8, 0.9, 1.0])

Dij = rand(3,3)
potential = HardSpheres(Dij)

LennardJones

Implements the Lennard-Jones pair interaction $u(r) = 4\epsilon [(\sigma/r)^{12} - (\sigma/r)^6]$.

Expects values ϵ and σ, which respecively are the strength of the potential and particle size.

Example:

potential = LennardJones(1.0, 2.0)

PowerLaw

Implements the power law pair interaction $u(r) = \epsilon (\sigma/r)^{n}$.

Expects values ϵ, σ, and n, which respecively are the strength of the potential and particle size.

Example:

potential = PowerLaw(1.0, 2.0, 8)

WCADivision{P<:Potential, T, UC}

fields

• potential::Potential
• cutoff : ($r_{c}$)
• U_c : $U(r=r_c)$

Splits the potential at the cutoff point using the WCA splitting rule. This means

\[u(r) = u_{SR}(r) + U_{LR}(r),\]

where $U_{LR}(r) = u(r)$ for $r > r_{c}$, and $U(r_{c})$ for $r < r_{c}$, and $USR(r) = 0$ for $r > r_{c}$, and $U(r) - U(r_{c})$ for $r < r_{c}$.