Engineering topics

Ancarani, L U

Publications and source records attributed to Ancarani, L U.

3 records

DOE OSTI2011

A special asymptotic limit of a Kampe de Feriet hypergeometric function appearing in nonhomogeneous Coulomb problems

In the investigation of two-body Coulomb Schroedinger equations with some types of nonhomogeneities, the particular solution can be expressed in terms of a two-variable Kampe de Feriet hypergeometric function. The asymptotic limit of the latter--for both variables being large but their ratio being a bound constant--is required in order to extract relevant physical information from the solutions. In this report the mathematical limit is provided. For that purpose, a particular series representation of the hypergeometric function--in terms of products of Kummer and Gauss functions--is first derived.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2010

Two-body Coulomb problems with sources

The two-body Coulomb Schroedinger equation with different types of nonhomogeneities are studied. The particular solution of these nonhomogeneous equations is expressed in closed form in terms of a two-variable hypergeometric function. A particular representation of the latter allows one to study efficiently the solution in the asymptotic limit of large values of the coordinate and hence the associated physics. Simple sources are first considered, and a complete analysis of scattering and bound states is performed. The solutions corresponding to more general (arbitrary) sources are then provided and written in terms of more general hypergeometric functions.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2010

Generating optimal Sturmian basis functions for atomic problems

In this paper we discuss the optimization of Sturmian basis functions by studying bound atomic systems within the configuration interaction method. Our investigation clearly shows how the fulfillment of correct physical boundary conditions at short and large distances from the nucleus improves the convergence rate of the method. This is illustrated first through a one-electron atom, and then with the two-electron systems. For the ground state of the helium atom, and with 35 Sturmian functions per electron and angular momenta, we obtain an energy of -2.903 712 820 a.u., outperforming previous similar calculations [Bromley and Mitroy, Int. J. Quantum Chem. 107, 1150 (2007)].

74 ATOMIC AND MOLECULAR PHYSICS↗