hoomd_script.pair Namespace Reference

Commands that create forces between pairs of particles. More...

Classes
class	coeff
	Defines pair coefficients. More...
class	nlist
	Interface for controlling neighbor list parameters. More...
class	pair
	Generic pair force. More...
class	lj
	Lennard-Jones pair force. More...
class	gauss
	Gaussian pair force. More...
class	slj
	Shifted Lennard-Jones pair force. More...
class	yukawa
	Yukawa pair force. More...
class	ewald
	Ewald pair force. More...
class	cgcmm
	CMM coarse-grain model pair force. More...
class	table
	Tabulated pair force. More...
class	morse
	Morse pair force. More...
class	dpd
	NVT Integration via Dissipative Particle Dynamics pair force. More...
class	dpd_conservative
	DPD Conservative pair force. More...
class	eam
	EAM pair force. More...
class	dpdlj
	NVT Integration via Dissipative Particle Dynamics pair force with a Lennard Jones conservative force. More...
class	force_shifted_lj
	Force-shifted Lennard-Jones pair force. More...

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Detailed Description

Commands that create forces between pairs of particles.

Generally, pair forces are short range and are summed over all non-bonded particles within a certain cutoff radius of each particle. Any number of pair forces can be defined in a single simulation. The net force on each particle due to all types of pair forces is summed.

Pair forces require that parameters be set for each unique type pair. Coefficients are set through the aid of the coeff class. To set this coefficients, specify a pair force and save it in a variable

 my_force = pair.some_pair_force(arguments...)

Then the coefficients can be set using the saved variable.

 my_force.pair_coeff.set('A', 'A', epsilon=1.0, sigma=1.0)
 my_force.pair_coeff.set('A', 'B', epsilon=1.0, sigma=2.0)
 my_force.pair_coeff.set('B', 'B', epsilon=2.0, sigma=1.0)

This example set the parameters epsilon and sigma (which are used in pair.lj). Different pair forces require that different coefficients are set. Check the documentation of each to see the definition of the coefficients.

See also:

Quick Start Tutorial