This type specifies the Sutton-Chen potential[37] with periodic boundary conditions (minimum image convention[53]). If no file named SCparams exists in the current directory the 12$ {-}$6 potential for gold is used. Otherwise the Sutton-Chen parameters $ n,\ m,\ \epsilon,\ c$ and $ a$ are read from this file in order. If the keyword PRESSURE is set in the odata file then a constant pressure optimisation is performed with the energy being minimised by golden section with respect to the cubic box size before taking another step. The cutoff is automatically changed in proportion to the change in box size. Otherwise the optimisations are performed at constant volume, with no relaxation of the unit cell. The bulk fcc nearest neighbour distance in the prevailing unit system is $ a/\sqrt{2}$, as above. Subroutines used: escp, dscp.

David Wales 2017-09-25