Photoabsorption spectra of small HgN clusters (N = 2–5) have been calculated using a diatomics-in-molecules interaction model and an atoms-in-molecules approach for transition probability calculations.

A hybrid method based on quantum mechanical formalism for electrons and a classical treatment for nuclei was used to study the dynamics of electronically ground state krypton dimer in collision with its parent gas. Two sets of collision cross-sections, namely non-reactive scattering and collision induced dissociation, were calculated from this method by using different sets of atomatom interaction potentials (neutral-neutral, ion-neutral). These cross-sections were injected in Monte Carlo simulations for the determination of Kr 2 + mobility, diffusion and dissociation rate constant. It is noteworthy that we also used an inverse method based on JWKB approximation to calculate a global momentum transfer collision cross-section without discerning the inelastic processes as dissociation. Thus, the transport coefficients obtained are also in a pretty good agreement with experimental data. All Monte Carlo simulations were performed at ambient pressure and temperature over a broad range of reduced electric field. Moreover, effects of Kr 2 + rovibronic excitations were also studied thoroughly in order to improve correlation between theoretical mobility calculations and experimental data available in the literature.

Collisions of electronically excited krypton dimers with krypton atoms are studied using ahybrid (quantum-classical) dynamical method, semi-empirical diatomics-in-molecules electronic Hamiltonian, and Monte Carlo modeling. Krypton dimer mobility in krypton gas and dimer disappearance rate constants have been calculated for abroad range of thereduced electric field and five lowest excited electronic states of thedimer ion. Comparison with calculations recently reported for theelectronic ground-state krypton dimer ion and with available experimental data is also provided. Two groups of the electronic states of the krypton dimer ion, resulting from a spin-orbit induced splitting, have been analyzed separately. Importantly, for both groups of states, the theoretical results bracket the experimental ones, therefore, considering mixtures of electronically excited states may strongly improve the agreement between theory and experiment. In addition, the effect of rotational-vibrational excitations in electronically excited krypton dimer ions is assessed and shown to also lead to an improved agreement between theory and experiment.

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Evolution of low-temperature Hg8 absorption spectrum with increased external pressure.