K V Rodriguez

Accurate and simple wavefunctions for the helium isoelectronic sequence with correct cusp conditions

Simple and accurate wavefunctions for the He atom and He-like isoelectronic ions are presented. These functions—the product of hydrogenic one-electron solutions and a fully correlated part—satisfy all the coalescence cusp conditions at the Coulomb singularities. Functions with different numbers of parameters and different degrees of accuracy are discussed. Simple analytic expressions for the wavefunction and the energy, valid for a wide range of nuclear charges, are presented. The wavefunctions are tested, in the case of helium, through the calculations of various cross sections which probe different regions of the configuration space, mostly those close to the two-particle coalescence points.

A simple parameter-free wavefunction for the ground state of two-electron atoms

We propose a simple and pedagogical wavefunction for the ground state of two-electron atoms which (i) is parameter free, (ii) satisfies all two-particle cusp conditions, (iii) yields reasonable ground-state energies, including the prediction of a bound state for H−. The mean energy, and other mean physical quantities, is evaluated analytically. The simplicity of the result can be useful as an easy-to-use wavefunction when testing collision models.

Study of two correlated electrons confined by harmonic potentials

We extend the Angular Correlated Configuration Interaction method to two confined correlated electrons confined by harmonic potentials.

Correlated n1,3S states for two-electron atoms in screened potentials

Two-electron atoms in screened and exponential cosine screened Coulomb potentials are studied. We have calculated within a Configuration Interaction approach, the ground and first excited states energies, and other mean values, for H−, He and Li+. We analyze their evolution with the screening parameters, and provide practical fits which allow for a practical and rapid evaluation for plasma applications.

Explicitly correlated Sturmian functions for structure and collision three-body problems

We introduce explicitly correlated Sturmian functions with appropriate boundary conditions to deal with both bound and scattering states of three-body systems.

Ground state for two-electron atoms in exponential-cosine-screened Coulomb potentials

We extend the Angular Correlated Configuration Interaction method to two-electron atoms placed in a plasma environment.