This uses Murrell's two- plus three-body
potential[48,49,50,51,52] with periodic boundary
conditions (minimum image convention.[53]
A `JMparams` file must exist as for type JC. (In previous versions the
first three lines of `JMparams` were assumed to contain
the square roots of 2, 3 and 6). Four additional real parameters must be given after the
search type and maximum step size specification, these being the , and dimensions
of the periodic cell and the cutoff, respectively. I do not think the code has been tested
for any non-cubic unit cells. The cutoff should not be greater than half the box length.[53]
Subroutines used: **jmep**, **jm2p**, **jm3p**.

David Wales
2017-11-22