For POTEntial=BIHArmonic, a two-sided harmonic function is used:
where
S is the scale factor specified by the SCALe statement, 
is the
Boltzmann constant, T is the temperature specified by the
TEMPerature
statement,
ceil is specified by the CEILing statement,
d, 
, and 
are specified by the
ASSIgn
statement:
The distance R is defined in Section 18.2.
The deviation 
is
defined as |R-d|.
