For POTential=SOFTsquare, the square-well function is used for distances within a specified ``switching" region (, specified by the RSWITch statement), whereas outside this region a ``soft" asymptote is used:

where is given by Eq. 18.9 and
**a** and **b** are determined by the program such that
is a smooth function at the point .
The
slope of the asymptote **c** is specified by the ASYMptote statement,
is specified by the RSWItch statement, and the
exponent **softexp** is specified
by the SOEXponent statement.
The distance **R** is defined in Section 18.2.

Sat Mar 11 09:37:37 PST 1995