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