Role Of Nuclear Motion Research Articles

Attosecond photoionization delays in molecules: The role of nuclear motion

Molecular photoionization delays are often analyzed by assuming that nuclei remain fixed during the ionization process since they move much more slowly than electrons. However, recent high-energy resolution and multicoincidence experiments have shown that nuclear motion can have a significant and visible effect on the measured ionization delays on the attosecond time scale. To analyze this behavior, we have chosen the simplest of all molecules, H2+, and performed nearly exact calculations of streaking and RABBIT (reconstruction of attosecond beatings by interferences in two-photon transitions) spectra by solving the time-dependent Schrödinger equation in full dimensionality, and retrieved the corresponding photoionization delays. We show that, when two-center effects are at play, nuclear motion is responsible for a substantial increase of the photoionization delays, in particular of the so-called continuum-continuum delays. The magnitude of such an increase is comparable to the absolute values of the measured delays. Published by the American Physical Society 2024

Correction to “On the Role of Nuclear Motion in Singlet Exciton Fission: The Case of Single‐Crystal Pentacene”

Correction to “On the Role of Nuclear Motion in Singlet Exciton Fission: The Case of Single‐Crystal Pentacene”

First-principles interpretation of electron transport through single-molecule junctions using molecular dynamics of electron attached states

The electron transport through the single-molecule junction of benzene-1,4-diamine (BDA) is modelled using ab initio quantum-classical molecular dynamics of electron attached states. Observations on the nature of the process are made by time-resolved analysis of energy differences, non-adiabatic transition probabilities and the spatial distribution of the excess electron. The role of molecular vibrations that facilitate the transport by being responsible for the periodic behaviour of these quantities is shown using normal mode analysis. The results support a mechanism involving the electron's direct hopping between the electrodes, without its presence on the molecule, with the prime importance of the bending vibrations that periodically alter the molecule–electrode interactions. No relevant differences are found between results provided by the ADC(2) and SOS-ADC(2) excited state models. Our approach provides an alternative insight into the role of nuclear motions in the electron transport process, one which is more expressive from the chemical perspective.

Role of Nuclear Motion in Double Ionization of Molecular Hydrogen by a Single Photon

We examine the origin of recently observed variations with internuclear distance (R) of the fully differential cross sections for double ionization of aligned H2 by absorption of a single photon. Using the results of fully converged numerical solutions of the Schrödinger equation, we show that these variations arise primarily from pronounced differences in the R dependence of the parallel and perpendicular components of the ionization amplitude. We also predict that R dependences should be readily observable in the asymmetry parameter for photodouble ionization, even in experimental measurements that are not differential in the energy sharings between ejected photoelectrons.

On the role of nuclear motions in electron and excitation transfer rates: Importance of transfer-integral dependence upon nuclear coordinate

The role of nuclear degrees of freedom in modifying the electron or exciton transfer rates between molecules is investigated. In addition to the usual Franck-Condon overlap factors which arise from the overlaps of initial and final vibrational states, we discuss a dependence of the transfer integral upon nuclear motions, a dependence which has been often cited, but nearly always ignored, in the usual dynamical theories of transfer processes. We show, within a Bom-Oppenheimer treatment, that the transfer integral dependence upon librational, rotational and vibrational modes can profoundly change both the rate itself and its functional dependences (upon temperature, upon orientation, etc.). Using a simple cosine form for the dependence of the transfer integral upon the modifying nuclear mode and a simple displaced-oscillator transformation, we obtain a closed-form solution for the transfer rate, which includes a new overlap factor arising from the dependence of the transfer integral upon nuclear coordinates. Some general remarks about the role of this dependence are made, and applications to particular transfer systems are briefly discussed.