Choosing the potential and its parameters

Probably the most important thing a user needs to control is the potential. Different potentials are represented by different classes; objects are created just as above, so for example:

  # generalized LJ potential (here m=18, n=4)
  potential = Pot_gLJ_m_n(18,4, cutoff_method=ShiftedPotential) 
  # inverse power-law (IPL) with exponent n=12
  potential = Pot_IPL_12(cutoff_method=ShiftedPotential)

To set parameters for the potential, call its SetParams method as described above. If a binary system is to be simulated, the parameters should be set separately for each interaction pair as follows

  potential.SetParams(0, 0, 1.00, 1.00, 1.12246)
  potential.SetParams(0, 1, 0.80, 1.50, 1.12246)
  potential.SetParams(1, 1, 0.88, 0.50, 1.12246)

Note that Newton's third law is assumed to hold, so setting the parameters for i=0 and j=1 automatically sets those for i=1 and j=0 (we could also have called SetParams with the latter). An overview of the available potentials is given in the user manual.