Lennard-Jones potential plus a variable quantity of the Axilrod-Teller
triple-dipole term[38,39] with units
The pre-multiplication factor for
the three-body term, , is specified by the PARAMS keyword.
If a multiplier of is specified the Axilrod-Teller derivatives
and energy are not calculated, thus providing a route to the pure Lennard-Jones potential
in reduced units. Subroutines used: ardiff, apairs, axdiff, axpairs.