Exact Simulation of Pigment-Protein Complexes Unveils Vibronic Renormalization of Electronic Parameters in Ultrafast Spectroscopy

TL;DR

This paper introduces a numerically exact simulation approach to analyze vibronic dynamics in pigment-protein complexes, revealing significant corrections to electronic parameters and insights into long-lived spectral oscillations.

Contribution

It presents a novel simulation method that accurately models multi-mode vibronic effects in pigment-protein complexes, improving interpretation of spectroscopic data.

Findings

Multi-mode vibronic effects cause significant corrections to electronic parameters.

Inclusion of full vibronic dynamics explains long-lived oscillations in spectra.

Method applied to chlorophyll-binding proteins and bacterial reaction centers.

Abstract

The primary steps of photosynthesis rely on the generation, transport, and trapping of excitons in pigment-protein complexes (PPCs). Generically, PPCs possess highly structured vibrational spectra, combining many discrete intra-pigment modes and a quasi-continuous of protein modes, with vibrational and electronic couplings of comparable strength. The intricacy of the resulting vibronic dynamics poses significant challenges in establishing a quantitative connection between spectroscopic data and underlying microscopic models. Here we show how to address this challenge using numerically exact simulation methods by considering two model systems, namely the water-soluble chlorophyll-binding protein of cauliflower and the special pair of bacterial reaction centers. We demonstrate that the inclusion of the full multi-mode vibronic dynamics in numerical calculations of linear spectra leads to systematic and quantitatively significant corrections to electronic parameter estimation. These multi-mode vibronic effects are shown to be relevant in the longstanding discussion regarding the origin of long-lived oscillations in multidimensional nonlinear spectra.