Calculation of shape-truncation functions for hexagonal cells Original Research Article

The semianalytical method for the calculation of the shape function coefficients which we developed by combining analytical and numerical techniques is now applied to cells with hexagonal symmetry. All values of the c/a ratio are taken into account and our calculated coefficients are used to evaluate three dimensional integrals that we frequently meet in electronic structure calculations, without imposing any approximations on the shape of the unit cell.