a few formatting fixes for pair style python

        # set coeffs: 48*eps*sig**12, 24*eps*sig**6,

        #              4*eps*sig**12,  4*eps*sig**6

        self.units = 'lj'

        self.coeff = {'lj'  : {'lj'  : (48.0,24.0,4.0,4.0)}}

        self.coeff = \{'lj'  : \{'lj'  : (48.0,24.0,4.0,4.0)\}\}

:pre

The class also has to provide two methods for the computation of the

potential energy and forces, which have be named {compute_force},

and {compute_energy}, which both take 3 numerical arguments:

  rsq   = the square of the distance between a pair of atoms (float) :li

  itype = the (numerical) type of the first atom :li

  rsq   = the square of the distance between a pair of atoms (float) :l

  itype = the (numerical) type of the first atom :l

  jtype = the (numerical) type of the second atom :ul

This functions need to compute the force and the energy, respectively,