pair_style dpd/conservative command

Syntax

pair_style dpd/conservative cutoff
  • cutoff = global cutoff for DPD interactions (distance units)

Examples

pair_style dpd/conservative 2.5
pair_coeff * * 3.0 2.5
pair_coeff 1 1 3.0

Description

Style dpd/conservative computes the conservative force for dissipative particle dynamics (DPD). The conservative force on atom I due to atom J is given by

_images/pair_dpd_conservative.jpg

where the weighting factor, omega_ij, varies between 0 and 1, and is chosen to have the following functional form:

_images/pair_dpd_omega.jpg

where Rij is a unit vector in the direction Ri - Rj, and Rc is the cutoff. Note that alternative definitions of the weighting function exist, but would have to be implemented as a separate pair style command.

Style dpd/conservative differs from the other dpd styles in that the dissipative and random forces are not computed within the pair style.

For style dpd/conservative, the pairwise energy is due only to the conservative force term Fc, and is shifted to be zero at the cutoff distance Rc. The pairwise virial is calculated using only the conservative term.

Style dpd/conservative requires the following coefficients to 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:

  • A (force units)
  • cutoff (distance units)

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


Restrictions

The pair style dpd/conservative is only available if LAMMPS is built with the USER-DPD package.