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... |

## 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