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### pair_style morse command

### pair_style morse/gpu command

### pair_style morse/opt command

Syntax:

    pair_style morse cutoff

    pair_style morse/gpu cutoff

    pair_style morse/opt cutoff

- cutoff = global cutoff for Morse interactions (distance units)

Examples:

    pair_style morse 2.5
    pair_style morse/opt 2.5
    pair_coeff * * 100.0 2.0 1.5
    pair_coeff 1 1 100.0 2.0 1.5 3.0

Description:

Style morse computes pairwise interactions with the formula

Rc is the cutoff.

The following coefficients must be defined for each pair of atoms types via the pair_coeff command as in the examples above, or in the data file or restart files read by the read_data or read_restart commands:

- D0 (energy units)
- alpha (1/distance units)
- r0 (distance units)
- cutoff (distance units)

The last coefficient is optional. If not specified, the global morse cutoff is used.

Style morse/opt is an optimized version of style morse that should give identical answers. Depending on system size and the processor you are running on, it may be 5-25% faster (for the pairwise portion of the run time).

Style morse/gpu is a GPU-enabled version of style morse. See more details below.

The morse/gpu style is identical to the morse style, except that each processor off-loads its pairwise calculations to a GPU chip. Depending on the hardware available on your system this can provide a speed-up. See the Running on GPUs section of the manual for more details about hardware and software requirements for using GPUs.

More details about these settings and various possible hardware configuration are in this section of the manual.

Additional requirements in your input script to run with GPU-enabled styles are as follows:

The newton pair setting must be off and fix gpu must be used. The fix controls the essential GPU selection and initialization steps.

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

None of these pair styles support mixing. Thus, coefficients for all I,J pairs must be specified explicitly.

All of these pair styles support the pair_modify shift option for the energy of the pair interaction.

The pair_modify table options is not relevant for the Morse pair styles.

None of these pair styles support the pair_modify tail option for adding long-range tail corrections to energy and pressure.

All of these pair styles write their information to binary restart files, so pair_style and pair_coeff commands do not need to be specified in an input script that reads a restart file.

These pair styles can only be used via the pair keyword of the run_style respa command. They do not support the inner, middle, outer keywords.

Restrictions:

The morse/opt style is part of the "opt" package. The morse/gpu style is part of the "gpu" package. They are only enabled if LAMMPS was built with those packages. See the Making LAMMPS section for more info.

Related commands:

pair_coeff

Default: none