exclude parameter.
The choices for exclusions
are none, 1-2, 1-3, 1-4, and scaled1-4.
With none, no atom pairs are excluded.
With 1-2, only atoms that are connected
via a linear bond are excluded.
With 1-3, any pair of atoms connected
via a bond or bonded to a common third atom are excluded.
With 1-4, any atoms that are connected by a linear bond,
or a sequence of two bonds, or a sequence of three bonds, are excluded.
With scaled1-4, exclusions are applied
in the same manner as the 1-3 setting,
but those pairs that are connected by
a sequence of 3 bonds are calculated using the modified 1-4 methods
described rather than the standard force calculations.