Linear Absorption Spectra from Explicitly Time-Dependent Equation-of-Motion Coupled-Cluster Theory
We report an explicitly time-dependent approach to the generation of linear absorption spectra for molecular systems within the framework of equation-of-motion (EOM) coupled-cluster (CC) theory. While most time-dependent CC approaches consider the perturbation and time-evolution of a CC wave function, the present work considers the time-evolution of a CC dipole function. The dipole function formalism introduces no approximations and requires the evolution of only one time-dependent quantity, either the left or right dipole function. This time-dependent framework can be used to compute linear absorption spectra for molecules with a high density of states over a broad spectral range, a case for which conventional frequency-domain computations may become impractical. We validate the approach by comparing absorption spectra for small molecules computed at EOM second-order approximate CC (CC2) and time-dependent EOM-CC2 (TD-EOM-CC2) levels of theory. TD-EOM-CC2 computations are also used to predict extreme ultraviolet absorption spectra for third-row ions that are in reasonable agreement with experiment.
Journal of Chemical Theory and Computation
Nascimento, D., & DePrince, A. (2016). Linear Absorption Spectra from Explicitly Time-Dependent Equation-of-Motion Coupled-Cluster Theory. Journal of Chemical Theory and Computation, 12 (12), 5834-5840. https://doi.org/10.1021/acs.jctc.6b00796