Characterization of multielectron dynamics in molecules: A multiconfiguration time-dependent Hartree-Fock picture

Using the framework of multiconfiguration theory, where the wavefunction Φ(t) of a many-electron system at time t is expanded as Φ(t)=∑ICI(t)ΦI(t) in terms of electron configurations {ΦI(t)}, we divided the total electronic energy E(t) as E(t)=∑I|CI(t)|2EI(t) . Here EI(t) is the instantaneous phase changes of CI(t) regarded as a configurational energy associated with ΦI(t). We then newly defined two types of time-dependent states: (i) a state at which the rates of population transfer among configurations are all zero; (ii) a state at which {EI(t)} associated with the quantum phases of CI(t) are all the same. We call the former time-dependent state a classical stationary state by analogy with the stationary (steady) states of classical reaction rate equations and the latter one a quantum stationary state. The conditions (i) and (ii) are satisfied simultaneously for the conventional stationary state in quantum mechanics. We numerically found for a LiH molecule interacting with a near-infrared (IR) field e(t...