Editing Intermolecular potential for c60 molecule

The '''Approximate non-conformal potential''' ('''ANC''') for the C60 fullerene is given by (Eq 6 in <ref>[http://dx.doi.org/10.1016/j.chemphys.2017.05.014 Jesús Eloy Ramos "Effective intermolecular potential and critical point for C60 molecule", Journal of Chemical Physics '''492''' pp. 5-11 (2017)]</ref>):

:<math>\Phi_{12}(z) =  \epsilon \left[ \frac{1-a}{(z^3/S +1 - 1/S)^{1/3} -a} \right]^{12} - 2\epsilon \left[ \frac{1-a}{(z^3/S +1 - 1/S)^{1/3} -a} \right]^{6} </math>

where
* <math>z := r/r_m</math>
* <math>r_m</math> = 1.0281 nm
* <math> a </math> = 0.09574 is the hard-core diameter in units of <math>r_m</math>
* <math> \epsilon </math> = 3297.28 K is the well depth
* <math>S</math> = 0.4120 is a softness parameter