Nonadiabatic molecular dynamics of photoexcited ${\rm Li}_2^+{\rm Ne}_n$ Li 2+ Ne n clusters

Abstract

We investigate the relaxation of photoexcited Li(2)(+) chromophores solvated in Ne(n) clusters (n = 2-22) by means of molecular dynamics with surface hopping. The simplicity of the electronic structure of these ideal systems is exploited to design an accurate and computationally efficient model. These systems present two series of conical intersections between the states correlated with the Li+Li(2s) and Li+Li(2p) dissociation limits of the Li(2)(+) molecule. Frank-Condon transition from the ground state to one of the three lowest excited states, hereafter indexed by ascending energy from 1 to 3, quickly drives the system toward the first series of conical intersections, which have a tremendous influence on the issue of the dynamics. The states 1 and 2, which originate in the Frank-Condon area from the degenerated nondissociative 1(2)Π(u) states of the bare Li(2)(+) molecule, relax mainly to Li+Li(2s) with a complete atomization of the clusters in the whole range of size n investigated here. The third state, which originates in the Frank-Condon area from the dissociative 1(2)Σ(u)(+) state of the bare Li(2)(+) molecule, exhibits a richer relaxation dynamics. Contrary to intuition, excitation into state 3 leads to less molecular dissociation, though the amount of energy deposited in the cluster by the excitation process is larger than for excitation into state 1 and 2. This extra amount of energy allows the system to reach the second series of conical intersections so that approximately 20% of the clusters are stabilized in the 2(2)Σ(g)(+) state potential well for cluster sizes n larger than 6.

Spectroscopy and Dynamics of K Atoms on Argon Clusters

“…30 It has been used recently to investigate the properties of highly excited Ba atoms at the surface of Ar clusters. 31 For alkali metals, the numerical developments are presented in detail in refs 7 and 30 and are not repeated here.…”

Nonadiabatic molecular dynamics simulation for carrier transport in a pentathiophene butyric acid monolayer

“…In recent years, we saw a surge of NAMD studies [25,26,27,28,29], from organic systems to nanostructures, showing the promise and people's interest of this approach. Unfortunately, the NAMD simulation can be extremely expensive.…”

Nonequilibrium Solvent Effects during Photodissociation in Liquids: Dynamical Energy Surfaces, Caging, and Chemical Identity

“…Most chemical reactions, including photodissociation reactions that use light to break chemical bonds, take place in solution. Since solution-phase reactions are inherently more complex than those in the gas phase, most studies of photodissociation and recombination dynamics have focused on simple diatomic molecules to elucidate solvent effects on chemical reaction dynamics, − with a particular emphasis on molecular iodine (I 2 ). − …”

“…Rather than assuming the solute moves on the same potential energy surface as in the gas phase, the solute could be thought of as moving along an effective potential energy surface where the solvent is at equilibrium with the solute, the so-called potential of mean force (PMF) . Such an approach can describe, on average, how the solvent will interact with and potentially alter the electronic structure of the solute, presuming that the solvent truly does remain in equilibrium throughout the course of the reaction. ,, For example, PMFs are appropriate for thinking about ion pairs in liquid water: solute−solvent structures identified in the ground-state PMF , have been associated with those found with X-ray absorption, neutron scattering, and Raman spectroscopy . And several groups have used PMFs to understand how solvent effects can alter electronic structure during proton transfer, electron transfer, proton-coupled electron transfer, hydride transfer, etc.…”

“…Ishida and Rossky , used excited-state PMFs to understand the solvent reorganization following the photoexcitation of a betaine dye. There also have been a few studies that used a semiempirical description to concoct the potential energy surfaces governing solute motion following photoexcitation in solution. , However, we are not aware of any investigations exploring the quantum mechanics of how solvents alter the electronic structure and excited-state reaction dynamics of molecules in liquids, and for photodissociation in particular, one would not expect an equilibrium description to properly account for the strong “caging” solvent collisions that promote recombination . Thus, one of the primary goals of this work is to explore the use of a rigorous formalism, based on the time integral of work, to describe nonequilibrium photodissociation dynamics in solution.…”