Quantum Nuclear Dynamics Pumped and Probed by Ultrafast Polarization Controlled Steering of a Coherent Electronic State in LiH

Abstract

The quantum wave packet dynamics following a coherent electronic excitation of LiH by an ultrashort, polarized, strong one-cycle infrared optical pulse is computed on several electronic states using a grid method. The coupling to the strong field of the pump and the probe pulses is included in the Hamiltonian used to solve the time-dependent Schrodinger equation. The polarization of the pump pulse allows us to control the localization in time and in space of the nonequilibrium coherent electronic motion and the subsequent nuclear dynamics. We show that transient absorption, resulting from the interaction of the total molecular dipole with the electric fields of the pump and the probe, is a very versatile probe of the different time scales of the vibronic dynamics. It allows probing both the ultrashort, femtosecond time scale of the electronic coherences as well as the longer dozens of femtoseconds time scales of the nuclear motion on the excited electronic states. The ultrafast beatings of the electronic coherences in space and in time are shown to be modulated by the different periods of the nuclear motion.

An open‐source framework for analyzing N‐electron dynamics. I. Multideterminantal wave functions

“…This finding is in agreement with previous theoretical studies on similar molecules. [104,105,108] The electronic flux density offers the main advantage of revealing all mechanistic features of the electron flow at first glance.…”

“…These methods build a hierarchy of electronic structure theories, where the description of electron correlation is improved systematically by considering either a larger active space or a higher degree of excitations. As a Full CI calculation is used as a reference, a well‐studied four‐electron molecule, the heteronuclear polar lithium hydride LiH, is chosen as a test system . We are particularly interested in the charge transfer state A , which is optically accessible from the electronic ground state X and lies in the Franck‐Condon region.…”

Spatial and temporal control of populations, branching ratios, and electronic coherences in LiH by a single one-cycle infrared pulse

“…LiH electronic states have been extensively studied by us [7,52,[58][59][60] and others. [61][62][63][64] The electronic states were computed at MRCI level using the quantum chemistry code MOLPRO [65], see Supplemental Materials (SM) for details.…”

“…The non-stationary character of the coherent state prepared by the pulse means that the LiH molecule will have a time-dependent dipole, μ t ( ) , [51,52] which includes both nuclear and electronic contributions: (2) and which has both a diagonal and a coherent, transition dipole, contribution. Figure 5 shows the time-dependent transition dipole component, that is, the part of the dipole that is non diagonal in the electronic states, , computed for the two pulses of opposite CEP used in In figure S4, in addition to the fast beating of ≈ 1.6 fs, which corresponds to the Σ 1 -Σ 2…”

“…[8,[41][42][43][44][45][46][47][48][49][50][51][52] We show that switching the CEP value of the pump pulse from 0 to π controls the fragmentation yields of the different dissociation asymptotes.…”