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The sinking of alkali cations in superfluid 4He nanodroplets is investigated theoretically using liquid 4He time-dependent density functional theory at zero temperature. The simulations illustrate the dynamics of the buildup of the first solvation shell around the ions. The number of helium atoms in this shell is found to linearly increase with time during the first stages of the dynamics. This points to a Poissonian capture process, as concluded in the work of Albrechtsen et al. on the primary steps of Na+ solvation in helium droplets [Albrechtsen et al., Nature 623, 319 (2023)]. The energy dissipation rate by helium atom ejection is found to be quite similar between all alkalis, the main difference being a larger energy dissipated per atom for the lighter alkalis at the beginning of the dynamics. In addition, the number of helium atoms in the first solvation shell is found to be lower at the end of the dynamics than at equilibrium for both Li+ and Na+, pointing to a kinetic rather than thermodynamical control of the snowball size for small and strongly attractive ions.
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.
Sujets
Dynamique quantique
Atomic collisions
Electronic Structure
Dissipative dynamics
ALGORITHM
CLASSICAL TRAJECTORY METHOD
Muonic hydrogen
Electron-surface collision
Contrôle cohérent
Dynamique moléculaire quantique
Anisotropy
Tetrathiafulvalene
COLLISION ENERGY
Anharmonicity
Coulomb presssure
Alkali-halide
Atomic scattering from surfaces
Théorie de la fonctionnelle de la densité
Dynamique non-adiabatique
Cope rearrangement
Cosmological constant
Electron transfer
ENERGY
Classical trajectory
Transport électronique
MCTDH
ELECTRON-NUCLEAR DYNAMICS
Effets transitoires
Electronic transport inelastic effects
ENTANGLEMENT
Dynamics
Deformation
Dissipation
Molecules
MODEL
Clusters
DEMO
Atomic clusters
DFTB
Calcium
Wave packet interferences
DRIVEN
Superfluid helium nanodroplets
DISSIPATION
Rydberg atoms
CAVITY
Coherent control
Dark energy
DENSITY
WAVE-PACKET DYNAMICS
Collisions des atomes
Fonction de Green hors-équilibre
CHEMICAL-REACTIONS
4He-TDDFT simulation
STATE
Cesium
Electric field
Diels-Alder reaction
Coordonnées hypersphériques elliptiques
Effets de propagation
QUANTUM OPTIMAL-CONTROL
Dynamique mixte classique
Density functional theory
Non-equilibrium Green's function
COHERENT CONTROL
Transitions non-adiabatiques
Theory
Collisions ultra froides
Agrégats
Composés organiques à valence mixte
Propagation effects
Ab initio calculations
Quantum dynamics
Bohmian trajectories
Collision frequency
DEPENDENT SCHRODINGER-EQUATION
Ultrashort pulses
COMPLEX ABSORBING POTENTIALS
Ab-initio
Cluster
Atom
ELECTRON DYNAMICS
AR
DIFFERENTIAL CROSS-SECTIONS
Slow light
Half revival
ENTROPY
Dissipative quantum methods
Effets isotopiques
ELECTRONIC BUBBLE FORMATION
Drops
Photophysics
DYNAMICS
Cryptochrome
Extra dimension
Casimir effect
Close-coupling
Ejection
Effets inélastiques
CONICAL INTERSECTION