We report on a successful implementation of the diabatic-by-sector method as applied to the computation of positive-energy diamagnetic Rydberg spectra of the alkali-metal atoms in a laboratory field (∼6 T). The method provides the quantum-defect parameters directly, and opens up the possibility of accounting for various spectral features quantum mechanically.

• Received 30 July 1991

DOI:https://doi.org/10.1103/PhysRevLett.67.3227