Time-dependent multiconfiguration self-consistent-field and time-dependent optimized coupled-cluster methods for intense laser-driven multielectron dynamics

TL;DR

This paper reviews advanced time-dependent multielectron simulation methods, TD-MCSCF and TD-OCC, for modeling intense laser-driven phenomena in atoms and molecules, emphasizing their theoretical foundations and computational implementations.

Contribution

It introduces and discusses the theoretical formulation and real-time implementation of TD-MCSCF and TD-OCC methods for high-field multielectron dynamics.

Findings

Flexible, systematically improvable multielectron descriptions

Gauge-invariant and Ehrenfest theorem-compliant formulations

Real-time simulations of ionization and harmonic generation

Abstract

We review time-dependent multiconfiguration self-consistent-field (TD-MCSCF) method and time-dependent optimized coupled-cluster (TD-OCC) method for first-principles simulations of high-field phenomena such as tunneling ionization and high-order harmonic generation in atoms and molecules irradiated by a strong laser field. These methods provide a flexible and systematically improvable description of the multielectron dynamics by expressing the all-electron wavefunction by configuration interaction expansion or coupled-cluster expansion, using time-dependent one-electron orbital functions. The time-dependent variational principle plays a key role to derive these methods satisfying gauge invariance and Ehrenfest theorem. The real-time/real-space implementation with an absorbing boundary condition enables the simulation of high-field processes involving multiple excitation and ionization. We present a detailed, comprehensive discussion of such features of TD-MCSCF and TD-OCC methods.