C60

C60, also known as Buckminsterfullerene is composed of carbon atoms.

 200 lightgrey C60.pdb C60

Models

Girifalco potential

The Girifalco intermolecular pair potential is given by [1] (Eq. 4):

${\displaystyle \Phi (r)=-\alpha \left[{\frac {1}{s(s-1)^{3}}}+{\frac {1}{s(s+1)^{3}}}-{\frac {2}{s^{4}}}\right]+\beta \left[{\frac {1}{s(s-1)^{9}}}+{\frac {1}{s(s+1)^{9}}}-{\frac {2}{s^{10}}}\right]}$

where

${\displaystyle s={\frac {r}{2a}}}$
${\displaystyle \alpha ={\frac {N^{2}A}{12(2a)^{6}}}}$
${\displaystyle \beta ={\frac {N^{2}B}{90(2a)^{12}}}}$

where ${\displaystyle N}$ is the number of atoms on each sphere, i.e. N=60.

Approximate non-conformal potential

The Approximate non-conformal potential (ANC) for the C60 fullerene is given by (Eq 6 in [2]):

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

where

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

Gel phase

Simulations of the Girifalco potential indicate a possible gel composed solely of C60 molecules [8]