In order for the minimum image convention to work correctly within
DL_POLY_2 , it is necessary to ensure that the cutoff applied to the
pair potentials does not exceed half the perpendicular width of the
simulation cell. (The perpendicular width is the shortest distance
between opposing cell faces.) Termination results if this is detected.
In NVE simulations this can only happen at the start of a simulation,
but in NPT, it may occur at any time.
Action:
Supply a cutoff that is less than half the cell width. If running
constant pressure calculations, use a cutoff that will accommodate
the fluctuations in the simulation cell. Study the fluctuations
in the OUTPUT file to help you with this.