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pair_style lj/smooth command

Syntax:

pair_style lj/smooth Rin cutoff 

Examples:

pair_style lj/smooth 8.0 10.0
pair_coeff * * 10.0 1.5
pair_coeff 1 1 20.0 1.3 7.0 9.0 

Description:

Style lj/smooth computes a LJ interaction with a force smoothing applied between the inner and outer cutoff.

The polynomial coefficients C1, C2, C3, C4 are computed by LAMMPS to cause the force to vary smoothly from Rin to Rc. At Rin the force and its 1st derivative will match the unsmoothed LJ formula. At Rc the force and its 1st derivative will be 0.0. IMPORTANT NOTE: this force smoothing causes the energy to be discontinuous both in its values and 1st derivative. This can lead to poor energy conservation. Plot the energy and force resulting from this formula via the pair_write command to see the effect.

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:

The last 2 coefficients are optional. If not specified, the global Rin and cutoff are used. Rin cannot be 0.0. If Rin = cutoff, then no force smoothing is performed for this type pair; the standard LJ formula is used.

Restrictions: none

Related commands:

pair_coeff

Default: none