Molecular calculations using the muffin-tin orbital method

Abstract

The spin density functional (SDF) formalism of Hohenberg, Kohn and Sham is used to calculate ground state properties of molecules. The SDF equations are solved using a muffin-tin orbital method due to Andersen, which includes nonmuffin-tin components of the potential self-consistently. The method is numerically efficient as it is formulated as a linear eigenvalue problem and the calculation of four center integrals is avoided. Binding energies, equilibrium separations, vibration frequencies, and dipole moments are calculated for a series of diatomic molecules. The results agree well with experiment and typical errors are of the order of 1 to 2 eV (binding energy), 0.1–0.2 a0 (equilibrium separation) and 100–200 cm−1 (vibration frequency). These results indicate that the SDF scheme gives a quantitative description of the change in energy and charge density associated with chemical bonding.