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Articles you may be interested inAccurate ab initio ro-vibronic spectroscopy of the X ̃ 2 Π CCN radical using explicitly correlated methods An ab initio study of the vibronic, spin-orbit, and magnetic hyperfine structure in the X Π 2 electronic state of NCO An ab initio study of the hyperfine structure in the X 2 Π electronic state of CCCH Ab initio study of the vibronic and spin-orbit structure in the X 2 Π electronic state of CCCH Potential energy surfaces for the electronic states of the HCCS radical correlating at linear nuclear arrangement with the A 2 ⌸ state are calculated by means of an extensive ab initio approach. They are used to compute the vibronic and spin-orbit structure of the A 2 ⌸ -X 2 ⌸ electronic transition. These calculations are carried out by means of a new variational approach based on the use of normal bending coordinates. The results of calculations question various interpretations of the available experimental data; on the other hand they do not offer reliable explanation of all features observed, pointing in this way at the shortages of the present, as well as of previous theoretical handling of the problem in question.

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In the present study, we report the results of a detailed theoretical investigation along with the experimental observations of chlorine-doped small lithium clusters. The cluster ions of the type LiCl (n ≥ m, n = 1-6, m = 1-3) were obtained by the evaporation of LiCl from a Knudsen cell as a chemical reactor in the temperature range between 1800 and 2700 K. Heterogeneous clusters with more than one Cl atom are produced and detected for the first time, and the experimental conditions for formation and stability are examined. The structural characteristics and stabilities of neutral and positively charged LiCl species are analyzed by using quantum chemistry methods. Doping lithium clusters with chlorine increases their stability, although there is a typical closed-shell-open-shell alternation in stability. Calculated dissociation energies are the best indicator of cluster stability of experimentally detected clusters. Heterogeneous lithium-chloride clusters can be viewed as species consisting of m negative Cl ions and a positively charged Li "cage"; upon ionization, an electron departs from the lithium cage. An important reason for the higher stability of closed-shell clusters is the delocalization of electrons over the lithium cage, which is more energetically favored than localization of electrons between two lithium atoms. According to their ionization energies, the titled clusters can be classified as "superalkalis".

The aim of the present study is to predict by means of ab initio calculations the vibronic and spin-orbit structure in the X (2)Π(u) electronic state of NC(4)N(+) and to elucidate some details in an observed laser-induced fluorescence spectrum of this species, particularly those interpreted in terms of the bending overtones and the spin-orbit splitting. The ground electronic state of NC(4)N(+) was investigated by density functional (B3LYP) and complete active space self-consistent field-multi-reference configuration interaction (CASSCF-MRCI) methods. The bending vibrational frequencies ω(T1) = 558 cm(-1), ω(T2) = 266 cm(-1), ω(C1) = 459 cm(-1), and ω(C2) = 113 cm(-1) were obtained. The spin-orbit coupling constant was calculated using state-average CASSCF wave functions in the framework of the MRCI method, and the value of A(SO) = -44 cm(-1) was determined. This quantity and the data for the bending frequencies and Renner parameters were employed for handling a combined effect of the vibronic and spin-orbit coupling, according to a model developed in our earlier studies.

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