Calculating excited states of molecular aggregates by the renormalized excitonic method

TL;DR

This paper extends the ab initio renormalized excitonic method (REM) to time-dependent density functional theory (TDDFT) for calculating excitation energies in molecular aggregates, achieving accurate results with reduced computational costs.

Contribution

The paper introduces the application of REM to TDDFT, enabling efficient and accurate excitation energy calculations for complex molecular systems.

Findings

REM-TDDFT yields excitation energies within 0.1 eV of standard TDDFT.

Computational time is reduced by an order of magnitude.

The method performs well across various molecular aggregate systems.

Abstract

In this paper, we apply the recently developed ab initio renormalized excitonic method (REM) to the excitation energy calculations of various molecular aggregates, through the extension of REM to the time-dependent density functional theory (TDDFT). Tested molecular aggregate systems include one-dimensional hydrogen-bonded water chains, ring crystals with $\pi$-$\pi$ stacking or van-der Waals interactions and the general aqueous systems with polar and non-polar solutes. The basis set factor as well as the effect of the exchange-correlation functionals are also investigated. The results indicate that the REM-TDDFT method with suitable basis set and exchange-correlation functionals can give good descriptions of excitation energies and excitation area for lowest electronic excitations in the molecular aggregate systems with economic computational costs. It's shown that the deviations of REM-TDDFT excitation energies from those by standard TDDFT are much less than 0.1 eV and the computational time can be reduced by one order.