The above approach can be applied to non-cubic boxes as well. For example, for a 3-dimensional (3D) orthorhombic box with cell dimension R cell j ( j = x, y, z), if r min j is the minimum distance between the current cell and the given α-group and if W j is the width of the group of cells in the j-th direction, r c is the minimum of {r min j }, and r f is given by