Intermolecular potential for c60 molecule

The Approximate non-conformal potential (ANC) for the C60 fullerene is given by (Eq 6 in ):

$\Phi _{12}(z)=\epsilon \left[{\frac {1-a}{(z^{3}/S+1-1/S)^{1/3}-a}}\right]^{12}-2\epsilon \left[{\frac {1-a}{(z^{3}/S+1-1/S)^{1/3}-a}}\right]^{6}$

where

• $z:=r/r_{m}$
• $r_{m}$ = 1.0281 nm
• $a$ = 0.09574 is the hard-core diameter in units of $r_{m}$
• $\epsilon$ = 3297.28 K is the well depth
• $S$ = 0.4120 is a softness parameter