Density functional theory calculation of ground state energy, dipole polarizability and hyperpolarizability of a confined helium atom

TL;DR

This study uses density functional theory to analyze how confinement affects the ground state energy, polarizability, and hyperpolarizability of a helium atom within a spherical box, revealing monotonic decrease and sign change under strong confinement.

Contribution

It introduces a method to compute ground-state properties and nonlinear optical responses of confined atoms using DFT and Kohn-Sham equations, highlighting effects of spatial confinement.

Findings

Polarizability decreases monotonically with confinement radius.

Hyperpolarizability decreases and changes sign under strong confinement.

Ground-state energy and density are effectively calculated within the confinement model.

Abstract

We calculate ground-state energies and densities of a helium atom confined in an impenetrable spherical box within density functional theory. These calculations are performed by variationally solving Kohn-Sham equation with the ground-state orbital expanded in terms of Slater-type orbitals. Using the ground-state densities we then calculate static linear polarizability and nonlinear hyperpolarizability and study their variation with the radius of confinement. We find that polarizability decreases monotonically with decreasing confinement radius and the hyperpolarizability not only decreases but also undergoes a change in sign in the strong confinement regime.