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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
Deformation
Effets inélastiques
Dynamics
Anisotropy
COLLISION ENERGY
DRIVEN
Tetrathiafulvalene
Effets de propagation
Dark energy
Propagation effects
Transport électronique
Dissipative dynamics
Theory
STATE
QUANTUM OPTIMAL-CONTROL
Théorie de la fonctionnelle de la densité
Effets transitoires
Casimir effect
Collisions des atomes
Electron transfer
Density functional theory
Muonic hydrogen
COHERENT CONTROL
Superfluid helium nanodroplets
Cope rearrangement
Bohmian trajectories
DYNAMICS
Dynamique moléculaire quantique
Ejection
Close-coupling
Contrôle cohérent
CLASSICAL TRAJECTORY METHOD
ELECTRON DYNAMICS
AR
Cosmological constant
4He-TDDFT simulation
Classical trajectory
Photophysics
Wave packet interferences
Dynamique mixte classique
Rydberg atoms
Atom
Cesium
Dynamique quantique
COMPLEX ABSORBING POTENTIALS
Effets isotopiques
Clusters
Coherent control
ELECTRON-NUCLEAR DYNAMICS
Atomic clusters
Ab-initio
DIFFERENTIAL CROSS-SECTIONS
Quantum dynamics
Collisions ultra froides
DEPENDENT SCHRODINGER-EQUATION
DFTB
DENSITY
Ultrashort pulses
Anharmonicity
DEMO
Atomic collisions
Agrégats
Alkali-halide
Electronic Structure
Cryptochrome
Coordonnées hypersphériques elliptiques
Atomic scattering from surfaces
Composés organiques à valence mixte
Calcium
ENTROPY
ENERGY
Extra dimension
Diels-Alder reaction
Cluster
Electric field
Dissipation
Coulomb presssure
CONICAL INTERSECTION
Dynamique non-adiabatique
DISSIPATION
ENTANGLEMENT
Fonction de Green hors-équilibre
Transitions non-adiabatiques
Collision frequency
Dissipative quantum methods
CAVITY
Drops
Half revival
MODEL
Molecules
Electronic transport inelastic effects
Non-equilibrium Green's function
ALGORITHM
ELECTRONIC BUBBLE FORMATION
CHEMICAL-REACTIONS
MCTDH
Ab initio calculations
Electron-surface collision
Slow light
WAVE-PACKET DYNAMICS