Search for long-lasting electronic coherence using on-the-fly ab initio semiclassical dynamics

Abstract

Using a combination of high-level ab initio electronic structure methods with efficient on-the-fly semiclassical evaluation of nuclear dynamics, we performed a massive scan of small polyatomic molecules searching for a long-lasting oscillatory dynamics of the electron density triggered by the outer-valence ionization. We observed that in most of the studied molecules, either the sudden removal of an electron from the system does not lead to the appearance of the electronic coherence or the created coherences become damped by the nuclear rearrangement on a time scale of a few femtoseconds. However, we report several so far unexplored molecules with the electronic coherences lasting up to 10 fs, which can be good candidates for experimental studies. In addition, we present the full-dimensional simulations of the electronic coherences coupled to nuclear motion in several molecules which were studied previously only in the fixed nuclei approximation.

On-the-Fly ab initio Semiclassical Evaluation of Electronic Coherences in Polyatomic Molecules Reveals a Simple Mechanism of Decoherence

“…Our simulations demonstrate (see Ref. [55] for more details) that the electronic coherences created after the ultrafast ionization become damped by the nuclear rearrangement on a time scale of a few femtoseconds in most of the studied molecules. However, we were able to identify several so far unexplored molecules with electronic coherences lasting up to 10 fs, which are, therefore, promising candidates for future experimental studies.…”

“…However, we were able to identify several so far unexplored molecules with electronic coherences lasting up to 10 fs, which are, therefore, promising candidates for future experimental studies. [55] Fig. 2…”

From chiral laser pulses to femto- and attosecond electronic chirality flips in achiral molecules

“…At longer times, however, the coupling of the electrons to the nuclei will cause decoherence 26 . The present system has exceptionally long decoherence time (compared to hundreds of others 27 ), fs (estimated in Supplementary Note 4 of SI by means of the methods of (Refs. 28 – 32 )).…”

Charge Migration in HCCI Cations Probed by Strong Field Ionization: Time-Dependent Configuration Interaction and Vibrational Wavepacket Simulations

“…Alternatively, the potential energy surfaces can be calculated on-the-fly and coupled with a fully quantum treatment of the vibrations in methods such as variational multi-configurational Gaussian, , ab initio multiple spawning, multi-configurational Ehrenfest, , etc. More approximate approaches include semiclassical methods that propagate frozen or thawed Gaussian wavepackets on-the-fly. − Instead of obtaining fitted potential energy surfaces or calculating them on-the-fly, the potential energy surfaces can be represented by local quadratic approximations, provided there are no complications such as surface crossings, double wells, or large anharmonicities. Arnold, Vendrell, and Santra have found this approach satisfactory for modeling decoherence in water, paraxylene, and phenylalanine. , Yang and co-workers − examined this approach in detail for the nuclear dynamics of a coherent superposition of the X and A states of iodoacetylene cation and successfully modeled the decoherence of charge migration.…”