Entwicklung und Implementierung zweikomponentiger Hartree-Fock- und Dichtefunktionalmethoden

Abstract

In the present work a selfconsistent treatment of the spin-orbit interaction is developed in the program system TURBOMOLE implemented and adopted. The underlying formalism deals with two-component Hartree-Fock- and density functional methods including the 'resolution-of-the-identity'-approximation for the Coulomb- and exchange operators. The spin-orbit interaction is included via effective core potentials for the heavier p-elements and at the all-electron level with the effective spin-orbit operator AMFI for the lighter elements. It was discovered that the selfconsistent treatment of the spin-orbit interaction with effective core potentials has special requirements on the basis sets especially on the flexibility of the inner shells. With additions to the existing basis sets the basis set error for the two-component treatment is similar to the one-component approach. The enhanced basis sets have the same quality for one- and two-component calculations. The focus of the applications was on clusters of the heavy main group elements thallium, lead, bismuth and polonium. The inclusion of the spin-orbit interaction gives a realistic estimation of the cohesive energy of the small and medium-sized clusters and highly symmetric structures which show at the one-component level Jahn-Teller distortions to be often preferred. The implemented two-component procedure on the Hartree-Fock-level or by application of hybrid density functionals can be applied for middle-sized systems with comparably large basis sets. The efficiency of the two-component DFT approach with pure density functionals is demonstrated for nanoparticles (ca. 2000 basis functions).