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Interactions between molecular hydrogen and ions are of interest in cluster science, astrochemistry and hydrogen storage. In dynamical simulations, H2 molecules are usually modelled as point particles, an approximation that can fail for anisotropic interactions. Here, we apply an adiabatic separation of the H2 rotational motion to build effective pseudoatom-ion potentials and in turn study the properties of (H2)nNa+/Cl− clusters. These interaction potentials are based on high-level ab initio calculations and Improved Lennard-Jones parametrizations, while the subsequent dynamics has been performed by quantum Monte Carlo calculations. By comparisons with simulations explicitly describing the molecular rotations, it is concluded that the present adiabatic model is very adequate. Interestingly, we find differences in the cluster stabilities and coordination shells depending on the spin isomer considered (para- or ortho-H2), especially for the anionic clusters.
Recent experiments have shown that translational energy loss is mainly mediated by electron–hole pair excitations for hydrogen atoms impinging on clean metallic surfaces. Inspired by these studies, quasi-classical trajectory simulations are here performed to investigate the energy transfer after scattering of hydrogen atoms off clean and hydrogen-covered tungsten (100) surfaces. The present theoretical approach examines the coverage effect of the preadsorbed hydrogen atoms, as was done recently for the (110) crystallographic plane in (J Phys Chem C 125:14075, 2021). As suggested, scattering can be described in terms of three different dynamical mechanisms, the contribution of which changes with coverage, which allow to rationalize the shape of the energy loss spectra.
We present quasi-classical trajectory calculations of the F + HCl reactive scattering, for total angular momentum equal zero and using a London–Eyring–Polanyi–Sato potential energy surface specifically developed for the title reaction. The reactive dynamics is investigated for a wide range of collision energies, from subthermal velocities up to kinetic energies significantly exceeding the dissociation energy of the reactant molecule. We focus here on the light- and heavy-atom exchange probability and mechanisms at hyperthermal collision velocities, whereas low-energy collisions (which dominate the evaluation of the reaction rate constant) are used for the purpose of validating the current implementation of the quasi-classical trajectory method in a symmetrical hyperspherical configuration space. In spite of the limitations of the potential energy surface, the present methodology yields reaction probabilities in agreement with previous experimental and theoretical results. The computed branching probabilities among the different reaction channels exhibit a mild dependence on the initial vibrational state of the diatomic molecule. Conversely, they show a marked sensitivity to the value of the impact angle, which becomes more pronounced for increasing collision energies.
The triatomic system NeI2 is studied under the consideration that the diatom is found in an excited electronic state (B). The vibrational levels (v=13, …, 23) are considered within two well-known theoretical procedures: quasi-classical trajectories (QCT), where the classical equations of motion for nuclei are solved on a single potential energy surface (PES), and the trajectory surface hopping (TSH) method, where the same are solved in a bunch of crossed vibrational PES (diabatic representation). The trajectory surface hopping fewest switches (TSHFS) is implemented to minimize the number of hoppings, thus allowing the calculations of hopping probability between the different PES's, and the kinetic mechanism to track the dissociation path. From these calculations, several observables such as, the lifetimes, vibrational and rotational energies (I2), dissociation channels, are obtained. Our results are compared with previous experimental and theoretical work.
Cold Rydberg atoms are a promising platform for quantum technologies and combining them with optical waveguides has the potential to create robust quantum information devices. Here, we experimentally observe the excitation of cold rubidium atoms to a large range of Rydberg S and D states through interaction with the evanescent field of an optical nanofiber. We develop a theoretical model to account for experimental phenomena present such as the AC Stark shifts and the Casimir-Polder interaction. This work strengthens the knowledge of Rydberg atom interactions with optical nanofibers and is a critical step toward the implementation of all-fiber quantum networks and waveguide QED systems using highly excited atoms.
Sujets
Cryptochrome
Dynamique moléculaire quantique
ELECTRON-NUCLEAR DYNAMICS
Drops
DRIVEN
Electric field
Rydberg atoms
CHEMICAL-REACTIONS
Collisions des atomes
Non-equilibrium Green's function
Diels-Alder reaction
DFTB
Molecules
Dynamique quantique
Quantum dynamics
Composés organiques à valence mixte
ELECTRONIC BUBBLE FORMATION
ENERGY
Half revival
Extra dimension
Density functional theory
MODEL
Electronic Structure
DIFFERENTIAL CROSS-SECTIONS
Effets isotopiques
Photophysics
COMPLEX ABSORBING POTENTIALS
WAVE-PACKET DYNAMICS
Bohmian trajectories
Atomic collisions
Dynamics
Dark energy
STATE
Muonic hydrogen
MCTDH
Agrégats
Ab initio calculations
DENSITY
DYNAMICS
Effets de propagation
ELECTRON DYNAMICS
Cope rearrangement
Clusters
Close-coupling
Théorie de la fonctionnelle de la densité
COHERENT CONTROL
AR
Collision frequency
Transport électronique
Electronic transport inelastic effects
Anisotropy
4He-TDDFT simulation
Superfluid helium nanodroplets
Propagation effects
Atomic scattering from surfaces
DISSIPATION
Classical trajectory
Dissipation
Ab-initio
Transitions non-adiabatiques
CAVITY
Contrôle cohérent
Ejection
ALGORITHM
QUANTUM OPTIMAL-CONTROL
Cosmological constant
Alkali-halide
Deformation
COLLISION ENERGY
CLASSICAL TRAJECTORY METHOD
Cesium
DEMO
Collisions ultra froides
Dynamique non-adiabatique
Dissipative dynamics
Coordonnées hypersphériques elliptiques
Fonction de Green hors-équilibre
Dynamique mixte classique
Slow light
ENTANGLEMENT
Casimir effect
Cluster
ENTROPY
Atomic clusters
Anharmonicity
Coherent control
Effets transitoires
Coulomb presssure
DEPENDENT SCHRODINGER-EQUATION
Electron transfer
CONICAL INTERSECTION
Tetrathiafulvalene
Atom
Dissipative quantum methods
Electron-surface collision
Theory
Effets inélastiques
Wave packet interferences
Calcium
Ultrashort pulses