\(\renewcommand{\AA}{\text{Å}}\)

pair_style sph/lj command

Accelerator Variants: sph/lj/gpu

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.

Note

Please note that the SPH PDF guide file has not been updated for many years and thus does not reflect the current syntax of the SPH package commands. For that please refer to the LAMMPS manual.

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)

Styles with a gpu, intel, kk, omp, or opt suffix are functionally the same as the corresponding style without the suffix. They have been optimized to run faster, depending on your available hardware, as discussed on the Accelerator packages page. The accelerated styles take the same arguments and should produce the same results, except for round-off and precision issues.

These accelerated styles are part of the GPU, INTEL, KOKKOS, OPENMP, and OPT packages, respectively. They are only enabled if LAMMPS was built with those packages. See the Build package page for more info.

You can specify the accelerated styles explicitly in your input script by including their suffix, or you can use the -suffix command-line switch when you invoke LAMMPS, or you can use the suffix command in your input script.

See the Accelerator packages page for more instructions on how to use the accelerated styles effectively.

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.

Default

none

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

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