Many-electron sturmians applied to atoms and ions

Goscinski's definition of Sturmian basis sets is generalized and applied to many-electron systems. It is shown that when such basis sets an used, the kinetic energy term disappears from the secular equation, the nuclear attra ction potential is already in diagonal form in the secular equation, the or bital exponents are automatically optimized, and good accuracy, including c orrelation effects, can be obtained directly with very few basis functions and without the use of the self-consistent field approximation. As an illus tration, the method is applied to the ground states and excited states of a toms and ions. (C) 1999 Elsevier Science B.V. All rights reserved.