pair_style lcbop command

Syntax

pair_style lcbop

Examples

pair_style lcbop
pair_coeff * * ../potentials/C.lcbop C

Description

The lcbop pair style computes the long-range bond-order potential for carbon (LCBOP) of (Los and Fasolino). See section II in that paper for the analytic equations associated with the potential.

Only a single pair_coeff command is used with the lcbop style which specifies an LCBOP potential file with parameters for specific elements. These are mapped to LAMMPS atom types by specifying N additional arguments after the filename in the pair_coeff command, where N is the number of LAMMPS atom types:

  • filename
  • N element names = mapping of LCBOP elements to atom types

See the pair_coeff doc page for alternate ways to specify the path for the potential file.

As an example, if your LAMMPS simulation has 4 atom types and you want the 1st 3 to be C you would use the following pair_coeff command:

pair_coeff * * C.lcbop C C C NULL

The 1st 2 arguments must be * * so as to span all LAMMPS atom types. The first C argument maps LAMMPS atom type 1 to the C element in the LCBOP file. If a mapping value is specified as NULL, the mapping is not performed. This can be used when a lcbop potential is used as part of the hybrid pair style. The NULL values are placeholders for atom types that will be used with other potentials.

The parameters/coefficients for the LCBOP potential as applied to C are listed in the C.lcbop file to agree with the original (Los and Fasolino) paper. Thus the parameters are specific to this potential and the way it was fit, so modifying the file should be done carefully.


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

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

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

This pair 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

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

This pair potential requires the newton setting to be “on” for pair interactions.

The C.lcbop potential file provided with LAMMPS (see the potentials directory) is parameterized for metal units. You can use the LCBOP potential with any LAMMPS units, but you would need to create your own LCBOP potential file with coefficients listed in the appropriate units if your simulation doesn’t use “metal” units.