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Details concerning the energetics and structure of the ion pair in gaseous chloroethane, obtained at the multi-reference configuration interaction with singles and doubles (MR-CISD) level, are given. It is formed in the third excited state (31A′), and it can be classified as a hydrogen-bonded contact ion pair, although from its total binding energy of 3.28 eV (including extensivity corrections, at the MR-CISD + Q level with the aug-cc-pVTZ basis set, and including zero-point energy corrections) only 0.14 eV is due to an underlying hydrogen bond. It is a highly polar structure, with a dipole moment of 9.56 D. As compared to previous systems for which the same type of bond has been observed, it has a much lower hydrogen-bond energy and a much larger distance between the charge centers. The three lowest frequency vibrational modes of the HBCIP correspond to intermolecular cation–anion modes. The structure here obtained brings important structural questions for HCFCs derived from chloroethane. [ABSTRACT FROM AUTHOR]

The energy eigenvalues for confined H 2 + molecule are computed by using the variational method. The approach proposed here uses a trial molecular function for the ground state composed of a linear combination of atomic orbitals for confined hydrogen atom; for other states, we build the trial molecular eigenfunctions inspired in atomic orbitals and by using the orthogonality of the wave functions. The molecule is confined in an impenetrable prolate spheroidal box. The atomic orbital for 1s state is built from a previous suggestion inspired by the factorization of the Schrödinger equation, and for 2s state, we used the Gram–Schmidt process to build a trial atomic function orthogonal with 1s trial function. The main contribution of this work is to propose new wave functions to be used for the confined hydrogen ion molecule. The results obtained are in agreement with other results present in the literature, and the trial functions proposed here can be used to study other confined molecules. [ABSTRACT FROM AUTHOR]

A series of cyclometalated platinum(II) complexes with similar molecular structures but distinct phosphorescence quantum yields were investigated. To explore the intersystem crossing (ISC) and radiative decay processes, we investigated the absorption and phosphorescence properties, spin–orbit coupling matrix elements, major ISC channels and phosphorescent transition rates. For the temperature-dependent nonradiative decay processes, the metal-centered excited states (3MC), the transition states, and the minimum energy crossing points were investigated with theoretical calculations. The way of temperature-independent nonradiative decay which has weak influence on nonradiative decay rate was also compared through the calculation of reorganization energy (λ). [ABSTRACT FROM AUTHOR]