Generalized potential harmonics and contracted sturmians

A formalism is described for choosing computationally manageable Sturmian basis sets which are automatically adapted to the requirements of particular physical problems. The method is a generalization and improvement of the potential harmonic technique of Fabre de la Ripelle, which is extensively used in nuclear and atomic physics. The present generalization is not restricted to hyperspherical coordinates, and the basis functions are characterized by a physically motivated grand principal quantum number, rather than the grand angular momentum quantum number. As an illustration, the simple example of a two-electron atom is presented.