Electronic Quantum Fluxes during Pericyclic Reactions Exemplified for the Cope Rearrangement of Semibullvalene

Abstract

The outcome of a pericyclic reaction is typically represented by arrows in the Lewis structure of the reactant, symbolizing the net electron transfer. Quantum simulations can be used to interpret these arrows in terms of electronic fluxes between neighboring bonds. The fluxes are decomposed into contributions from electrons in so-called pericyclic orbitals, which account for the mutation of the Lewis structure for the reactant into that for the product, in other valence and in core orbitals. Series of time-integrated fluxes of pericyclic electrons can be assigned to the arrows, for example 0.09-0.23 electrons for Cope rearrangement of semibullvalene, with hysteresis-type time evolutions for 27.3 fs. This means asynchronous electronic fluxes during synchronous rearrangement of all the nuclei. These predictions should become observable by emerging techniques of femto-to attosecond time-resolved spectroscopy.

Electron Flow in Reaction Mechanisms—Revealed from First Principles

“…This problem can be alleviated in natural resonance theory (NRT), [24] but the discrete Lewis structures becoming relevant along ar eaction path still must be identified and chosen, [23] which is not always easy.Similar ambiguities in the discrete choice and physical meaning of resonance structures occur in valence bond (VB) theory. [28,29]), [30] or in previous work by Andrae et al, [31] where arrows represent electron flux between orbital density surfaces derived by Pipek-Mezey localization, here the curly arrows would represent ac hange in the bond orbitals themselves along the reaction path. We thus conjectured that the transformation of IBOs can also be followed along reaction paths,a nd that this movement of local orbitals-not of pairs of electrons,w hich are indistinguishable-is the information encoded in the curly arrows of mechanisms.Unlike in NRTor VB theory,w here arrows indicate shifts in weight between dominant resonance structures (e.g.R efs.…”

The adiabatic limit of the exact factorization of the electron-nuclear wave function

“…As a consequence, the electronic current density vanishes and the continuity equation is violated. [8][9][10][11][12][13] For similar reasons, the vibrational circular dichroism computed within the BOA requires corrections [14][15][16][17] to yield agreement with experimental measurements. Various approaches 5,6,11,12,15,[17][18][19][20] have been proposed to cure these inconsistencies perturbatively.…”

An efficient method to study highly excited states at the ab initio level and application to ultralong Rydberg CsNe molecules

“…[1][2][3][4] For small systems direct ab initio calculations of the PESs 5-7 have provided fundamental guidance for full dimensional quantum dynamics. For large systems, reduced dimensional treatments also cover the essential information of molecular processes.…”