Semiclassical description of nuclear dynamics moving through complex-valued single avoided crossings of two electronic states

In our paper a compact representation of the density as a function of a few observables is examined for the coupled electron-nuclear dynamics unfolding on three electronic states. The time-evolution of the density, populations and coherences, is accurately captured by the time-evolution of only nine coefficients, the Lagrange multipliers of these observables. We use a specific example of the isotope effect in atto-pumped N<sub>2</sub> to show that both classical and quantal effects of mass are well reproduced by this compact description. Simple analytical results for the surprisal are given, which allows a factorization of these two effects.

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Electron and nuclear dynamics following ionisation of modified bismethylene-adamantane

Faraday Discussions ◽

10.1039/c6fd00067c ◽

2016 ◽

Vol 194 ◽

pp. 95-115 ◽

Cited By ~ 14

Author(s):

Morgane Vacher ◽

Fabio E. A. Albertani ◽

Andrew J. Jenkins ◽

Iakov Polyak ◽

Michael J. Bearpark ◽

...

Keyword(s):

Electron Transfer ◽

Wave Packet ◽

Half Life ◽

Electronic States ◽

Nuclear Motion ◽

Hole Density ◽

Electron Dynamics ◽

Nuclear Dynamics ◽

Bond Lengths ◽

Methylene Groups

We have simulated the coupled electron and nuclear dynamics using the Ehrenfest method upon valence ionisation of modified bismethylene-adamantane (BMA) molecules where there is an electron transfer between the two π bonds. We have shown that the nuclear motion significantly affects the electron dynamics after a few fs when the electronic states involved are close in energy. We have also demonstrated how the non-stationary electronic wave packet determines the nuclear motion, more precisely the asymmetric stretching of the two π bonds, illustrating “charge-directed reactivity”. Taking into account the nuclear wave packet width results in the dephasing of electron dynamics with a half-life of 8 fs; this eventually leads to the equal delocalisation of the hole density over the two methylene groups and thus symmetric bond lengths.

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Structure and electronic properties of the doubly charged diatomic dications BeX2+ (X = Na, K)

Canadian Journal of Physics ◽

10.1139/cjp-2015-0300 ◽

2016 ◽

Vol 94 (1) ◽

pp. 1-8 ◽

Cited By ~ 2

Author(s):

Chedli Ghanmi ◽

Mohamed Farjallah ◽

Hamid Berriche ◽

Abdullah G. Al-Sehemi

Keyword(s):

Electronic Properties ◽

Electronic States ◽

Theoretical Data ◽

Spectroscopic Properties ◽

Basis Sets ◽

Gaussian Basis Sets ◽

Transition Dipole ◽

Dependent Polarization ◽

Avoided Crossings ◽

Doubly Charged

The structural and electronic properties of the doubly charged diatomic dications BeX2+ (X = Na, K) have been systematically investigated. The ab initio calculations method is based on the use of non-empirical pseudopotentials for the Be2+, Na+, and K+ cores, Gaussian basis sets, and parameterized l-dependent polarization potentials. The potential energy curves and their spectroscopic properties for the low-lying electronic states of 2Σ+, 2Π, and 2Δ symmetries have been determined for the species BeNa2+ and BeK2+ for the first time. Results show, for each diatomic dication, that the ground and the first excited electronic states are repulsive. For both systems, for which no experimental and theoretical data are available, we discuss our results by comparing their potential energies with similar systems. Numerous avoided crossings between electronic states of 2Σ+ and 2Π symmetries have been localized and analyzed. Their existence is related to the interaction between the electronic states and to the charge transfer process between the two ionic structures Be(2+)X and Be(+)X(+). Furthermore, the transition dipole functions from the ground state to the 2-102Σ+ and between neighbor electronic states of 2Σ+ symmetry, revealed many abrupt changes, which are localized at particular distances corresponding to the positions of the avoided crossings.

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Control of nuclear dynamics in the benzene cation by electronic wavepacket composition

Communications Chemistry ◽

10.1038/s42004-021-00485-3 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Thierry Tran ◽

Graham A. Worth ◽

Michael A. Robb

Keyword(s):

Extreme Ultraviolet ◽

Initial Conditions ◽

Chemical Reactivity ◽

Electronic States ◽

Time Dependent ◽

Electronic Control ◽

Electron Dynamics ◽

Nuclear Dynamics ◽

Successive Passage ◽

Dynamics Simulations

AbstractThe study of coupled electron-nuclear dynamics driven by coherent superpositions of electronic states is now possible in attosecond science experiments. The objective is to understand the electronic control of chemical reactivity. In this work we report coherent 8-state non-adiabatic electron-nuclear dynamics simulations of the benzene radical cation. The computations were inspired by the extreme ultraviolet (XUV) experimental results in which all 8 electronic states were prepared with significant population. Our objective was to study the nuclear dynamics using various bespoke coherent electronic state superpositions as initial conditions in the Quantum-Ehrenfest method. The original XUV measurements were supported by Multi-configuration time-dependent Hartree (MCTDH) simulations, which suggested a model of successive passage through conical intersections. The present computations support a complementary model where non-adiabatic events are seen far from a conical intersection and are controlled by electron dynamics involving non-adjacent adiabatic states. It proves to be possible to identify two superpositions that can be linked with two possible fragmentation paths.

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Methods to Calculate Electronic Excited-state Dynamics For Molecules on Large Metal Clusters with Many States: Ensuring Fast Overlap Calculations and a Robust Choice of Phase

10.26434/chemrxiv-2021-t433b ◽

2021 ◽

Author(s):

Hsing-Ta Chen ◽

Junhan Chen ◽

Vale Cofer-Shabica ◽

Zeyu Zhou ◽

Vishikh Athavale ◽

...

Keyword(s):

Excited State ◽

Collective Excitation ◽

Metal Cluster ◽

Computational Cost ◽

Electronic States ◽

Relaxation Processes ◽

Nuclear Dynamics ◽

Excited State Dynamics ◽

Electronic Excited State ◽

Unified Protocol

We present an efficient set of methods for propagating excited-state dynamics involving a large number of electronic states based on a CIS electronic state overlap scheme. Specifically, (i) following Head-Gordon et al, we implement an exact evaluation of the overlap of singly-excited electronic states at different nuclear geometries using a biorthogonal basis, and (ii) we employ a unified protocol for choosing the correct phase for each adiabat at each geometry. For many-electron systems, the combination of these techniques significantly reduces the computational cost of integrating the electronic Schrodinger equation and imposes minimal overhead on top of the underlying electronic structure calculation. As a demonstration, we calculate the electronic excited-state dynamics for a hydrogen molecule scattering off a silver metal cluster, focusing on high-lying excited states where many electrons can be excited collectively and crossings are plentiful. Interestingly, we find that the high-lying, plasmon-like collective excitation spectrum changes with nuclear dynamics, highlighting the need to simulate non-adiabatic nuclear dynamics and plasmonic excitations simultaneously. In the future, the combination of methods presented here should help theorists build a mechanistic understanding of plasmon-assisted charge transfer and excitation energy relaxation processes near a nanoparticle or metal surface.

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The Density Matrix via Few Dominant Observables: The Quantum Interference in the Isotope Effect for Atto-Pumped N2

10.26434/chemrxiv.14401643.v1 ◽

2021 ◽

Author(s):

Ksenia Komarova ◽

Francoise Remacle ◽

Raphael D. Levine

Keyword(s):

Density Matrix ◽

Time Evolution ◽

Isotope Effect ◽

Lagrange Multipliers ◽

Quantum Interference ◽

Electronic States ◽

Compact Representation ◽

Nuclear Dynamics ◽

Analytical Results

In our paper a compact representation of the density as a function of a few observables is examined for the coupled electron-nuclear dynamics unfolding on three electronic states. The time-evolution of the density, populations and coherences, is accurately captured by the time-evolution of only nine coefficients, the Lagrange multipliers of these observables. We use a specific example of the isotope effect in atto-pumped N<sub>2</sub> to show that both classical and quantal effects of mass are well reproduced by this compact description. Simple analytical results for the surprisal are given, which allows a factorization of these two effects.

Download Full-text