Time-dependent density-matrix functional theory for biexcitonic phenomena

TL;DR

This paper develops a time-dependent density-matrix functional theory approach to accurately model biexcitonic phenomena in solids, enabling calculation of biexcitonic binding energies with improved theoretical foundations.

Contribution

It introduces a novel TDDMFT framework for biexcitons based on reduced density matrices, allowing finite binding energy calculations with an adiabatic approximation.

Findings

Finite biexcitonic binding energies obtained for bulk semiconductors.

The method captures higher-order correlation effects in optical processes.

Application to a contact biexciton model demonstrates practical utility.

Abstract

We formulate a time-dependent density-matrix functional theory (TDDMFT) approach for higher-order correlation effects like biexcitons in optical processes in solids based on the reduced two-particle density-matrix formalism within the normal orbital representation. A TDDMFT version of the Schr\"odinger equation for biexcitons in terms of one- and two-body reduced density matrices is derived, which leads to finite biexcitonic binding energies already with an adiabatic approximation. Biexcitonic binding energies for several bulk semiconductors are calculated using a contact biexciton model.