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

Abstract

We review the time-dependent multiconfiguration self-consistent-field (TD-MCSCF) method and the 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.

Real-Time Equation-of-Motion Coupled-Cluster Cumulant Green’s Function Method: Heterogeneous Parallel Implementation Based on the Tensor Algebra for Many-Body Methods Infrastructure

“…This approximation is well-suited for strong-field physics, where consideration of optimal orbitals is crucial to obtain meaningful results. Such approaches provide a gauge-invariant description of the time-dependent properties of interest and satisfy the Ehrenfest theorem due to the use of variationally optimized orbitals. − Despite this advantage, such methods ,, are ill-suited for large-scale applications, especially when simulations involve core-hole states of chemical systems containing many active occupied electrons. Other developments in time-dependent electronic structure theory and time-dependent coupled-cluster methods ,− are reviewed elsewhere.…”