Power-law potential¶

This module implements the (inverse) power-law potential,

$U\left(r_{ij}\right) = \epsilon_{ij} \left(\frac{\sigma_{ij}}{r_{ij}}\right)^{n} \/,$

for the interaction between two particles of species $i$ and $j$ with the power-law index $n$ .

class halmd.mdsim.potentials.power_law(args)¶

Construct power-law potential.

Parameters:

args (table) – keyword arguments
args.particle – instance, or sequence of two instances, of halmd.mdsim.particle
args.epsilon (table) – matrix with elements $\epsilon_{ij}$ (defaults to 1)
args.sigma (table) – matrix with elements $\sigma_{ij}$ (defaults to 1)
args.cutoff (table) – matrix with elements $r_{\text{c}, ij}$
args.index (number) – power-law index $n$ (defaults to 12)

If all elements of a matrix are equal, a scalar value should be passed instead.

Note

The cutoff is only relevant with halmd.mdsim.forces.pair_trunc.

r_cut_sigma¶: Matrix with elements $r_{\text{c}, ij}$ in units of $\sigma_{ij}$ .