pair_style sph/lj command — LAMMPS documentation

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# pair_style sph/lj command

## Syntax

    pair_style sph/lj

## Examples

    pair_style sph/lj
    pair_coeff * * 1.0 2.4

## Description

The sph/lj style computes pressure forces between particles according to the Lennard-Jones equation of state, which is computed according to Ree’s 1980 polynomial fit (Ree). The Lennard-Jones parameters epsilon and sigma are set to unity. This pair style also computes Monaghan’s artificial viscosity to prevent particles from interpenetrating (Monaghan).

See this PDF guide to using SPH in LAMMPS.

The following coefficients must be defined for each pair of atoms types via the pair_coeff command as in the examples above.

- \(\nu\) artificial viscosity (no units)

- h kernel function cutoff (distance units)

## Mixing, shift, table, tail correction, restart, rRESPA info

This style does not support mixing. Thus, coefficients for all I,J pairs must be specified explicitly.

This style does not support the pair_modify shift, table, and tail options.

This style does not write information to binary restart files. Thus, you need to re-specify the pair_style and pair_coeff commands in an input script that reads a restart file.

This style can only be used via the pair keyword of the run_style respa command. It does not support the inner, middle, outer keywords.

## Restrictions

As noted above, the Lennard-Jones parameters epsilon and sigma are set to unity.

This pair style is part of the SPH package. It is only enabled if LAMMPS was built with that package. See the Build package page for more info.

## Related commands

pair_coeff, pair_sph/rhosum

## Default

none

(Ree) Ree, Journal of Chemical Physics, 73, 5401 (1980).

(Monaghan) Monaghan and Gingold, Journal of Computational Physics, 52, 374-389 (1983).