The interaction type contains informations about which potentials the simulation should use for the atoms in the system. This type is not intended to be manupulated directly, but rather through the add_interaction!() function.

add_interaction!(universe, potential, atoms...[; computation=:auto; kwargs...])

Add an interaction between the atoms atomic types, using the potential potential function in the universe.

This function accept many keywords arguments to tweak the potential computation methode used to effectively compute the potential. The main keyword is computation which default to :auto. It can be set to other values to choose another computation method than the default one.

julia> # Setup an universe with four atoms: two He and one Ar
julia> top = Topology();

julia> add_atom!(top, Atom("He")); add_atom!(top, Atom("He"));

julia> add_atom!(top, Atom("Ar")); add_atom!(top, Atom("Ar"));

julia> universe = Universe(UnitCell(), top);

# Use default values for everything
julia> add_interaction!(universe, LennardJones(0.23, 2.2), "He", "He")

# Set the cutoff to 7.5 A
julia> add_interaction!(universe, LennardJones(0.3, 2.5), "He", "Ar", cutoff=7.5)

# Use table computation with 3000 points, and a maximum distance of 5A
julia> add_interaction!(universe, Harmonic(40, 3.3), "Ar", "Ar", computation=:table, numpoints=3000, rmax=5.0)

Using non-default computation

By default, the computation algorithm is automatically determined by the potential function type. ShortRangePotential are computed with CutoffComputation, and all other potentials are computed by DirectComputation. If we want to use another computation algorithm, this can be done by providing a computation keyword to the add_interaction! function. The following values are allowed:

  • :direct to use a DirectComputation;
  • :cutoff to use a CutoffComputation. The cutoff can be specified with the cutoff keyword argument;
  • :table` to use a TableComputation. The table size can be specified with the numpoints keyword argument, and the maximum distance with the rmax keyword argument.