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lammps/doc/pair_style_dpd.txt
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pair_style_dpd.txt
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"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
:link(lws,http://lammps.sandia.gov)
:link(ld,Manual.html)
:link(lc,Section_commands.html#comm)
:line
pair_style dpd command :h3
[Syntax:]
pair_style dpd T cutoff seed :pre
T = temperature (temperature units)
cutoff = global cutoff for DPD interactions (distance units)
seed = random # seed (integer > 0 and < 900000000) :ul
[Examples:]
pair_style dpd 1.0 2.5 34387
pair_coeff * * 3.0 1.0
pair_coeff 1 1 3.0 1.0 1.0 :pre
[Description:]
Style {dpd} computes a force field for dissipative particle dynamics
(DPD) following the exposition in "(Groot)"_#Groot. The force
on atom I due to atom J is given as a sum of 3 terms
:c,image(Eqs/pair_dpd.jpg)
where FC is a conservative force, FD is a dissipative force, and FR is
a random force. Rij is a unit vector in the direction Ri - Rj, Vij is
the vector difference in velocities of the two atoms = Vi - Vj, alpha
is a Gaussian random number with zero mean and unit variance, dt is
the timestep size, and w(r) is a weighting factor that varies between
0 and 1. Rc is the cutoff. Sigma is set equal to sqrt(2 T gamma),
where T is a parameter in the pair_style command.
The following coefficients must be defined for each pair of atoms
types via the "pair_coeff"_pair_coeff.html command as in the examples
above, or in the data file or restart files read by the
"read_data"_read_data.html or "read_restart"_read_restart.html
commands:
A (force units)
gamma (force/velocity units)
cutoff (distance units) :ul
The last coefficient is optional. If not specified, the global DPD
cutoff is used. Note that sigma is set equal to sqrt(2 T gamma),
where T is the temperature set by the "pair_style"_pair_style.html
command so it does not need to be specified.
[Restrictions:] none
This style is part of the "dpd" package. It is only enabled if LAMMPS
was built with those package. See the "Making
LAMMPS"_Section_start.html#2_2 section for more info.
[Related commands:]
"pair_coeff"_pair_coeff.html
[Default:] none
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