The orthorhombic cell is also a common periodic boundary, which closely resembles the cubic cell in use. In DL_POLY_2 the cell is defined with principle axes passing through the centres of the faces. For an orthorhombic cell with sidelengths D (in X-direction), E (in Y-direction) and F (in Z-direction), the cell vectors appearing in the CONFIG file should be: (D,0,0); (0,E,0); (0,0,F). Note the origin of the atomic coordinates is the centre of the cell.
The orthorhombic boundary condition can be used with the Ewald summation method.
The orthorhomic MD cell.