Studies on some exponential-screened Coulomb potentials

TL;DR

This paper employs the generalized pseudospectral method to accurately compute the bound-state spectra of exponential-screened Coulomb potentials, including higher and excited states, with significant improvements over existing methods.

Contribution

It introduces a highly accurate computational approach for eigenvalues of screened Coulomb potentials, especially for higher and excited states, surpassing previous methods in precision.

Findings

Eigenvalues computed with up to eleven significant figures.

First-time accurate calculation of excited states up to n=18.

GESC eigenstates obtained with greater accuracy than existing literature.

Abstract

The generalized pseudospectral method is employed to study the bound-state spectra of some of the exponentially screened Coulomb potentials, \emph{viz.}, the exponential cosine screened Coulomb (ECSC) and general exponential screened Coulomb (GESC) potential, with special emphasis on \emph{higher} states and \emph{stronger} interaction. Eigenvalues accurate up to eleven significant figures are obtained through a non-uniform optimal spatial discretization of the radial Schr\"odinger equation. All the 55 eigenstates of ECSC potential with $n \le 10$ and 36 eigenstates of GESC potential with $n \le 8$ are considered for arbitrary values of the screening parameter, covering a wide range of interaction. Excited states as high as up to $n=18$ have been computed with high accuracy for the first time. Excellent agreement with the literature data has been observed in all cases. All the GESC eigenstates are calculated with much greater accuracy than the existing methods available in literature. Many $l \ne 0$ states of this potential are reported here. In both cases, a detailed variation of energies with respect to the parameters in potential is monitored.