RESUMEN
Photoabsorption spectra of He N + ${{\rm{He}}_N^ + }$ clusters, N=5-9, have been calculated using a diatomics-in-molecules like electronic structure model and a path-integral Monte Carlo sampling method. A qualitative change in the calculated spectra has been observed at N=9, which has been interpreted in terms of a structural transformation in the clusters consisting in a transition from trimer-like ionic cores observed for N≤7 to dimer-like ionic cores prevailing in He 9 + ${{\rm{He}}_9^ + }$ through an intermediate state (comparable abundances of both types of ionic cores) observed in He 8 + ${{\rm{He}}_8^ + }$ . The calculated spectra have been thoroughly compared with an earlier calculation on He 3 + ${{\rm{He}}_3^ + }$ , He 4 + ${{\rm{He}}_4^ + }$ , and He 10 + ${{\rm{He}}_{10}^ + }$ reported from our group and data available for the same cluster sizes from an experiment.
RESUMEN
A quantum formalism and classical treatment have been used for electrons and nuclei, respectively, in a hybrid method in order to study the dynamics of electronically ground-state ionic xenon dimer, Xe2+, in its parent gas. A semiempirical Diatomics In Molecules approach has been used to model the effective electronic Hamiltonian with different sets of input diatomic potentials (ionic and neutral). Non-reactive scattering and collision induced dissociation cross-sections have first been calculated and then injected in a Monte Carlo code for the simulations of the transport coefficients and dissociation rate constant calculated at ambient temperature and atmospheric pressure. Selected transport coefficients, such as Xe2+ mobility for which experimental measurements are available, have been compared to experimental results while transversal and longitudinal diffusion coefficients are compared to pseudo-experimental data obtained from inverse method calculations. Investigation of rotational-vibrational effects and the influence of different sets of ionic and neutral diatomic potentials have been studied.
RESUMEN
Photoabsorption spectra of Hg8 have been calculated at various cluster temperatures and external pressures. A diatomics-in-molecules method has been used to model cluster electronic structure and classical isothermal-isobaric Monte Carlo simulations have been employed for sampling representative cluster configurations. Contributions of different structural isomers of the Hg8 cluster have been analyzed and related to structural transitions in the cluster, particularly those induced by an increased pressure.
RESUMEN
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. Absorption cross-sections are provided over a broad range of photon energies, Ephot = 4.0-7.5 eV, as calculated for various cluster temperatures ranging between T = 0 K and T = 40 K. Quantum as well as temperature-induced delocalization of nuclear positions has been taken into account at various levels using classical and quantum (path-integral) Monte Carlo methods as well as sampling from the square of cluster vibrational ground-state wavefunctions. A thorough comparison of the calculated data with available experimental records is also provided.
