Development of computational methods for large molecules, semiempirical theory (MNDO and its extensions, methods with orthogonalization corrections, semiempirical GUGACI for electronically excited states, analytic derivatives), combined quantum mechanical/molecular mechanical approaches (QM/MM coupling schemes, free-energy calculations), corresponding software development (MNDO99, ChemShell).

Development and application of ab initio methods for accurate prediction of vibration-rotation spectra of small molecules.

Application of computational methods for studying a large variety of chemical phenomena, including density functional calculations on homogeneous catalysis by transition metal compounds and QM/MM calculations on biocatalysis by enzymes.