Multipole polarizabilities of spherically confined hydrogen atom and positronium in screened Coulomb potential

Abstract

The static multipole polarizabilities of the hydrogen atom interacting with a screened Coulomb potential confined in an impenetrable spherical box are calculated in the sum‐over‐states formalism. The system eigenenergies and wave functions are produced by employing the generalized pseudospectral method. High‐precision results are obtained to resolve the discrepancies between previous predictions, and used to analyze the critical behavior of the system with varying the confinement radius and screening parameter. A scaling law of the multipole polarizabilities with respect to the nuclear charge and electron reduced mass is proposed. Based on the scaling law we extend the investigation to the spatially confined positronium atom in a screened Coulomb potential by utilizing a reduced one‐electron model. The results are in good agreement with previous estimates. However, it is conjectured that when the confinement radius is small the confined positronium atom should be treated more reasonably by an effective two‐electron model.

Diffusion Monte Carlo calculations of the polarizability of a confined hydrogen atom: benchmarking and application to high symmetry wells

“…This number has been optimized through numerical tests: increasing the number of mesh elements does not have a significant effect on the sampled quantities, while it increases statistical fluctuations thus requiring more calculation time. Results have been validated with a comparison with (Cohen et al 2008, Saha et al 2011, He et al 2023, finding a quite good agreement, as shown in figure 1. The residual difference in the case of very large confinement radii is relatively unimportant, since we are interested in the behavior produced by the confinement, that is reproduced very accurately.…”