The cubic MD cell.
The cubic MD cell is perhaps the most commonly used in simulation and has the advantage of great simplicity. In DL_POLY_2 the cell is defined with the principle axes passing through the centres of the faces. Thus for a cube with sidelength D, the cell vectors appearing in the CONFIG file should be: (D,0,0); (0,D,0); (0,0,D). Note the origin of the atomic coordinates is the centre of the cell.
The cubic boundary condition can be used with the Ewald summation method.