Fully parameter-free calculation of optical spectra for insulators, semiconductors and metals from a simple polarization functional

TL;DR

This paper introduces a fully parameter-free, physically grounded density-functional method using a simple polarization functional within time-dependent current-density-functional theory to accurately predict optical spectra of various materials without empirical parameters.

Contribution

It presents a novel, parameter-free approach for calculating optical spectra that is both accurate and computationally efficient, avoiding empirical broadening parameters.

Findings

Accurately reproduces optical spectra of insulators, semiconductors, and metals.

Eliminates the need for ad-hoc broadening parameters.

Computational cost comparable to random-phase approximation calculations.

Abstract

We present a fully parameter-free density-functional approach for the accurate description of optical absorption spectra of insulators, semiconductors and metals. We show that this can be achieved within time-dependent current-density-functional theory using a simple dynamical polarization functional. We derive this functional from physical principles that govern optical spectra. Our method is truly predictive because not a single parameter is used. In particular, we do not use an \textit{ad-hoc} material-dependent broadening parameter to compare theory to experiment as is usually done. Our approach is numerically efficient; the cost equals that of a calculation within the random-phase approximation.