Short Range Potentials

Functional forms for short range potentials

Below are listed the interaction forms available for short range non-bonded interactions between atoms, with energy and force equations provided in full. Parameters are listed in the input order expected by Dissolve.

Keyword	Parameters	Description
`LJ`	$ϵ$ $σ$	Standard Lennard-Jones 12-6 potential. $E = 4 ϵ ({(\frac{σ}{r})}^{12} - {(\frac{σ}{r})}^{6})$ $F = - 48 ϵ (\frac{σ^{12}}{r^{13}} - \frac{1}{2} \frac{σ^{6}}{r^{7}})$ Cross-terms between atom types with this form are generated via the Lorenz-Berthelot combination rules: $σ_{i j} = \frac{σ_{i} + σ_{j}}{2}, ϵ_{i j} = \sqrt{ϵ_{i} ϵ_{j}}$
`LJGeom`	$ϵ$ $σ$	Standard Lennard-Jones 12-6 potential as defined for `LJ`, but utilising purely geometric rules when generating cross-terms: $σ_{i j} = \sqrt{σ_{i} σ_{j}}, ϵ_{i j} = \sqrt{ϵ_{i} ϵ_{j}}$
`Buckingham`	`A` `B` `C`	Buckingham exp-6 potential: $E = A \exp (- B r) - \frac{C}{r^{6}}$ $F = B A \exp (- B r) + 6 \frac{C}{r^{7}}$

Last modified March 18, 2025: feat: Add Buckingham exp6 potential for SpeciesBonds (#2081) (2c0966cd2)