Chirality of weakly bound complexes: the potential energy surfaces for the hydrogen-peroxide-noble-gas interactions.

We consider the analytical representation of the potential energy surfaces of relevance for the intermolecular dynamics of weakly bound complexes of chiral molecules. In this paper we study the H2O2-Ng (Ng=He, Ne, Ar, Kr, and Xe) systems providing the radial and the angular dependence of the potential energy surface on the relative position of the Ng atom. We accomplish this by introducing an analytical representation which is able to fit the ab initio energies of these complexes in a wide range of geometries. Our analysis sheds light on the role that the enantiomeric forms and the symmetry of the H2O2 molecule play on the resulting barriers and equilibrium geometries. The proposed theoretical framework is useful to study the dynamics of the H2O2 molecule, or other systems involving O-O and S-S bonds, interacting by non-covalent forces with atoms or molecules and to understand how the relative orientation of the O-H bonds changes along collisional events that may lead to a hydrogen bond formation or even to selectivity in chemical reactions.

Normal and hyperspherical mode analysis of NO-doped Kr crystals upon Rydberg excitation of the impurity.

Molecular dynamics simulations and both normal mode and hyperspherical mode analyses of NO-doped Kr solid are carried out in order to get insights into the structural relaxation of the medium upon electronic excitation of the NO molecule. A combined study is reported on the time evolution of the cage radius and on the density of vibrational states, according to the hyperspherical and normal mode analyses. For the hyperspherical modes, hyper-radial and grand angular contributions are considered. For the normal modes, radial and tangential contributions are examined. Results show that the first shell radius dynamics is driven by modes with frequencies at approximately 47 and approximately 15 cm-1. The first one is related to the ultrafast regime where a large part of the energy is transmitted to the lattice and the second one to relaxation and slow redistribution of the energy. The density of vibrational states gamma(omega) is characterized by a broad distribution of bands peaking around the frequencies of approximately 13, approximately 19, approximately 25, approximately 31, approximately 37, approximately 47, and approximately 103 cm-1 (very small band). The dominant modes in the relaxation process were at 14.89, 23.49, and 53.78 cm-1; they present the largest amplitudes and the greatest energy contributions. The mode at 14.89 cm-1 is present in both the fit of the first shell radius and in the hyper-radial kinetic energy spectrum and resulted the one with the largest amplitude, although could not be revealed by the total kinetic energy power spectrum.