Electronic structure calculations by the linear rigorous cellular method

Abstract

A modified version of Altmann's rigorous cellular method is presented. The new approach completely removes various practical drawbacks of Altmann's original method without affecting its unmatched flexibility. Instead of expanding the wave function in terms of partial waves which are generated at the band energies sought, we use partial waves and their energy derivatives at some suitably chosen energy. The one-particle energies are found by minimizing the expectation value of the true crystal Hamiltonian. Thereby non-spherical oscillations of the crystal potential within each cell are included. Moreover, the new approach is shown to be easily adaptable to a fully relativistic treatment. Open structures, such as covalently bound crystals, thin films, clusters of atoms and molecules, are just as tractable as close-packed structures. The progress achieved is demonstrated by first results on the electronic structure offcc lanthanum (including relativistic effects) and that of a (100) tungsten monolayer. The new approach is conceptually related to Andersen's LMTO-method with which it shares decisive virtues. However, the formal structure of our method is considerably simpler and its accuracy appears to be somewhat larger.