Extended dissipaton theory for higher-order bath couplings and application to non-Condon spectroscopy with anharmonicity

TL;DR

This paper introduces an extended dissipaton theory that models arbitrary order bath couplings, enabling accurate simulations of complex non-Condon spectra with anharmonicity and solvent effects in condensed-phase systems.

Contribution

The work generalizes dissipaton theory to include higher-order bath couplings, providing an exact and efficient method for complex environmental interactions in spectroscopy.

Findings

Anharmonicity significantly influences vibronic features.

Higher-order bath couplings affect optical spectra.

The extended theory accurately simulates complex spectral effects.

Abstract

In this work, we develop an extended dissipaton theory that generalizes the environmental couplings beyond the conventional linear and quadratic forms, enabling the treatment of arbitrary order of bath couplings. Applying this theoretical framework to the condensed-phase non-Condon spectroscopy, we demonstrate the interplay of anharmonicity, non-Condon and solvent effects on optical spectra. Precise simulations are carried out with high efficiency on linear absorption spectra involving the above mentioned correlated effects. We exhibit how an anharmonic potential modulates the vibronic feature, offering insights into the role of nonlinear environmental couplings in spectroscopic signatures and exemplifying the success of the extended dissipaton formalism as an exact and efficient method for higher-order bath couplings.