Semiclassical Quantization of the Helium Atom

Abstract

We report on recent investigations of the classical and semiclassical properties of the helium atom. We show that regular as well as chaotic classical motion of the electrons exists. Semiclassically, both types of motion require a separate treatment. Stability islands in phase space are quantized via a torus-quantization-type procedure, whereas a periodic-orbit cycle expansion approach accounts for the states associated with chaotic electron pair motion. The results are compared with accurate ab initio quantum calculations.