Polarizabilities of Intermediate Sized Lithium Clusters From Density-Functional Theory

TL;DR

This study uses density-functional theory to analyze the static dipole polarizability of lithium clusters up to 22 atoms, revealing size-dependent trends and magnetic state variations.

Contribution

It provides a comprehensive database of lithium cluster polarizabilities and explores the effects of geometry and size on their electronic properties using advanced computational methods.

Findings

Average polarizability decreases with cluster size.

Significant anisotropy changes are observed with different conformations.

Clusters with odd numbers of atoms can exhibit elevated spin states.

Abstract

We present a detailed investigation of static dipole polarizability of lithium clusters containing up to 22 atoms. We first build a database of lithium clusters by optimizing several candidate structures for the ground state geometry for each size. The full polarizability tensor is determined for about 5-6 isomers of each cluster size using the finite-field method. All calculations are performed using large Gaussian basis sets, and within the generalized gradient approximation to the density functional theory, as implemented in the NRLMOL suite of codes. The average polarizability per atom varies from 11 to 9 Angstrom^3, within the 8-22 size range and show smoother decrease with increase in cluster size than the experimental values. While the average polarizability exhibits a relatively weak dependence on cluster conformation, significant changes in the degree of anisotropy of the polarizability tensor are observed. Interestingly, in addition to the expected even odd (0 and 1 $\mu_B$) magnetic states, our results show several cases where clusters with an odd number of Li atoms exhibit elevated spin states (e.g. 3 $\mu_B$).