Research interests are quantum-mechanical
perturbation theory, summation of divergent perturbation series, quasiclassical
methods for resonant states. Specifically, Stark effect and 1/D-expansion
(where D is the dimensionality of space) for various quantum-mechanical
problems, such as screened Coulomb potentials, Stark and Zeeman effects,
helium-like ions, and two-centre-Coulomb problem.
Recently, worked on
self-consistent-field version of the semiclassical perturbation theory for molecules,
new schemes to sum perturbation series for resonances,
estimating stability of atoms with a variable nuclear charge
(finding "critical" charges).