Band structure calculation for realistic (non-muffin-tin) potentials based on the rigorous cellular method

Altmann's cellular method in which the Bloch states are determined by minimizing the mean square mismatch of a finite partial wave expansion at the cell boundaries, is shown to be readily adaptable to non-muffin-tin potentials. As a first test, the new method is applied to a nonspherically symmetric potential of aluminum and checked against a self-consistent muffin-tin potential, the former chosen such that its spherical average coincides with the latter. The non-muffin-tin effects turn out to be very small, as is expected for face-centered cubic lattices.