Linearly truncated Lennard-Jones potential¶

This module implements the Lennard-Jones potential with a linear truncation scheme (which is equivalent to a shifted force),

$U_\text{LJ}\left(r_{ij}\right) = 4\epsilon_{ij} \left( \left(\frac{\sigma_{ij}}{r_{ij}}\right)^{12} - \left(\frac{\sigma_{ij}}{r_{ij}}\right)^6 + (r_{ij} - r_c)\cdot F_c \right)$

for the interaction between two particles of species $i$ and $j$ . Here, $r_c$ denotes the cutoff distance and $F_c = - U_\text{LJ}(r_c)$ the force at the cutoff for the untruncated potential.

This linear truncation scheme modifies the potential drastically and at all distances by adding a constant force, and we do not recommend it for future work. It is mainly provided for historical reasons to connect to existing data and publications. Please refer to the local r⁴ truncation scheme for an alternative.

References¶

S. K. Das, J. Horbach, K. Binder, M. E. Fisher, and J. V. Sengers, J. Chem. Phys. 125, 024506 (2006)
S. Toxvaerd and J. C. Dyre, J. Chem. Phys. 134, 081102 (2011)
S. Toxvaerd, O. J. Heilmann, and J. C. Dyre, J. Chem. Phys. 136, 224106 (2012)

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

Construct linearly truncated Lennard-Jones 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 $r_{\text{c}, ij}$