Ab initio determination of polarizabilities and van der Waals coefficients of Li atoms using the relativistic CCSD(T) method

TL;DR

This paper introduces a fully ab initio relativistic coupled-cluster method to accurately determine van der Waals coefficients and polarizabilities of lithium atoms, avoiding traditional sum-over-states approaches.

Contribution

The authors develop a novel technique using relativistic CCSD(T) theory to compute polarizabilities and van der Waals coefficients without sum-over-states, applicable to low-lying Li states.

Findings

Calculated dipole and quadrupole polarizabilities for Li states.

Determined off-diagonal polarizabilities between low-lying states.

Provided new ab initio data for Li atom interactions.

Abstract

We report a new technique to determine the van der Waals coeffcients of lithium (Li) atoms based on the relativistic coupled-cluster theory. These quantities are determined using the imaginary parts of the scalar dipole and quadrupole polarizabilities, which are evaluated using the approach that we have proposed in [1]. Our procedure is fully ab initio, and avoids the sum-over-the-states method. We present the dipole and quadrupole polarizabilities of many of the low-lying excited states of Li. Also, the off-diagonal dipole and quadrupole polarizabilites between some of the low-lying states of Li are calculated.