Articles you may be interested inNormal and hyperspherical mode analysis of NO-doped Kr crystals upon Rydberg excitation of the impurity Structural dynamics in quantum solids. I. Steady-state spectroscopy of the electronic bubble in solid hydrogens Excitation of the A(3s) Rydberg state of NO leads to an extensive rearrangement of the environment, which we have investigated by classical molecular dynamics simulations and normal mode analysis, using pair potentials from the literature. We find that the medium response is independent of the details at long range of the excited state NO A-Ar potential, stressing the fact that it is mainly driven by the short range repulsive forces between the Rydberg electron and the matrix atoms. We establish the inertial character of the first shell response in the initial 100-150 fs after excitation, as the next shells are silent over this time scale. The expansion of the first shell at early times, induces the propagation of a supersonic wave along the ͑011͒ axis of the crystal, which define 12 linear chains of atoms with the impurity. The early time response is followed by vibrational coherences with a complex behavior. The normal modes analysis of the crystal shell by shell shows good agreement with the power spectra of the MD trajectories. It allows us to identify the most significant modes in the medium response. Overall, the dynamics of the system may be regarded as that of a NOAr 12 supermolecule, embedded in an Ar lattice and undergoing vibrational energy redistribution.

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Activated surface diffusion with interacting adsorbates is analyzed within the Linear ResponseTheory framework. The so-called interacting single adsorbate model is justified by means of a two-bath model, where one harmonic bath takes into account the interaction with the surface phonons, while the other one describes the surface coverage, this leading to defining a collisional friction. Here, the corresponding theory is applied to simple systems, such as diffusion on flat surfaces and the frustrated translational motion in a harmonic potential. Classical and quantum closed formulas are obtained. Furthermore, a more realistic problem, such as atomic Na diffusion on the corrugated Cu(001) surface, is presented and discussed within the classical context as well as within the framework of Kramer's theory. Quantum corrections to the classical results are also analyzed and discussed.

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Within a generalized Langevin framework for open quantum systems, the cyclic evolution of a twolevel system is analyzed in terms of the geometric phase extended to dissipative systems for Ohmic friction. This proposal is applied to the dynamics of chiral molecules where the tunneling and parity violating effects are competing. The effect of different system-bath coupling functions in the dissipated energy is shown to be crucial to understand the behavior of the geometric phase as well as the decoherence displayed by the corresponding interference patterns.

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A canonical framework for chiral two-level systems coupled to a bath of harmonic oscillators is developed to extract, from a stochastic dynamics, the thermodynamic equilibrium values of both the population difference and coherences. The incoherent and coherent tunneling regimes are analyzed for an Ohmic environment in terms of a critical temperature defined by the maximum of the heat capacity. The corresponding numerical results issued from solving a non-linear coupled system of equations are fitted to approximate path-integral analytical expressions beyond the so-called non-interacting blip approximation in order to determine the different time scales governing both regimes.

The chelated enol isomer of 2-chloromalonaldehyde (2-ClMA) is experimentally characterized for the first time by IR and Raman spectroscopies. The spectra are obtained by trapping the molecule in cryogenic matrices and analyzed with the assistance of theoretical calculations. Experiments were performed in argon, neon and para-hydrogen matrices. The results highlight puzzling matrix effects, beyond site effects, which are interpreted as due to a tunneling splitting of the vibrational levels related to the proton transfer along the internal hydrogen bond (IHB). 2-ClMA is thus one of the very few molecules in which the H tunneling has been observed in cryogenic matrices. The comparison with its parent molecule (malonaldehyde) shows experimentally and theoretically the weakening of the IHB upon chlorination, with a reduced cooperative effect in the resonance assisted hydrogen bond. In addition, the Cl substitution induces an important stabilization of two open enol conformers. These two open forms appear in the spectra of as-deposited samples, meaning that, in contrast with other well-studied molecules of the same family (β-dialdehydes and β-diketones), they are present in the gas phase at room temperature.