Uniform semiclassical and accurate quantum calculations of complex energy eigenvalues for the hydrogen atom in a uniform electric field

Uniform semiclassical and accurate quantum calculations of complex energy eigenvalues for the hydrogen atom in a uniform electric field are presented. In both the quantum and semiclassical approaches, explicit advantage is taken of the separability of the problem in either parabolic or squared parabolic coordinates. Good agreement is obtained between the quantum and semiclassical results. Comparison is made with previous semiclassical and quantum calculations. In particular, improved accuracy is obtained for a number of quantum results given by Damburg and Kolosov (1976).