These types specify Sutton-Chen potentials of the appropriate
form.[37]
Three additional real parameters must be specified using the *PARAMS* keyword
in the `odata` file,
namely Sutton and Chen's , and , in this order.
The nearest neighbour distance in the prevailing unit system is
. Hence,
using
corresponds to a unit system where the bulk nearest-neighbour distance is 1.
Subroutines used: **scdiff**.

David Wales
2018-03-24