Theoretical investigation of the He-I 2(E 3Π g) ion-pair state: Ab initio intermolecular potential and vibrational levels

We present a theoretical study on the potential energy surface and vibrational bound states of the E electronic excited state of the HeI 2 van der Waals system. The interaction energies are computed using accurate ab initio methods and large basis sets. Relativistic small-core effective core potentials in conjunction with a quintuple-zeta quality basis set are employed for the heavy iodine atoms in multireference configuration interaction calculations for the 3A ′ and 3A ″ states. For the representation of the potential energy surface we used a general interpolation technique for constructing potential surfaces from ab initio data based on the reproducing kernel Hilbert space method. The surface presents global and local minima for T-shaped configurations with well-depths of 33.2 and 4.6cm -1, respectively. Vibrational energies and states are computed through variational quantum mechanical calculations. We found that the binding energy of the HeI 2(E) T-shaped isomer is 16.85cm -1, in excellent agreement with recent experimental measurements. In lieu of more experimental data we also report our predictions on higher vibrational levels and we analyze the influence of the underlying surface on them. This is the first attempt to represent the potential surface of such a highly excited electronic state of a van der Waals complex, and it demonstrates the capability of the ab initio technology to provide accurate results for carrying out reliable studies to model experimental data. © 2012 American Institute of Physics.This work has been supported by the MICINN Grant Nos. FIS2010-18132 and FIS2011-29596-C02-01.Peer Reviewe

Ab initio potential energy curves of the valence, Rydberg and ion-pair states of iodine monochloride, ICl

11 pags.; 4 figs.; 2 tabs.We present for the first time a coherent ab initio study of 39 states of valence, Rydberg, and ion-pair character of the diatomic interhalogen ICl species through large scale multireference variational methods including spin-orbit effects coupled with quantitative basis sets. Various avoided crossings are responsible for a non-adiabatic behaviour creating a wonderful vista for its theoretical description. Our molecular constants are compared with all available experimental data with the aim to assist experimentalists especially in the high energy regime of up to ~95,000 cm(-1). © 2014 AIP Publishing LLC.R.P. acknowledges support from MICINN Grant No. FIS2011-29596-C02-01, COST Actions CM1002 (CODECS), and CM1204 (XLIC).Peer Reviewe

The nature of the chemical bond in BeO0,−, BeOBe+,0,−, and in their hydrogenated products HBeO0,−, BeOH, HBeOH, BeOBeH+,0,−, and HBeOBeH

The nature of the chemical bond in BeO0,−, BeOBe+,0,−, and in their hydrogenated products HBeO0,−, BeOH, HBeOH, BeOBeH+,0,−, and HBeOBeH has been studied through single and multi reference correlation methods. In all these species, excited and ionized atomic states participate in a resonant way making chemically possible molecules that have been termed hypervalent and explain also the “incompatible” geometrical structure of some species. © 2017 Author(s)

The Nature of the Chemical Bond in BeF- and Related Species

The beryllium atom represents a curiosity. Its ground state valency is zero, so it should not form chemical bonds. Nevertheless Be is a metal and can form stable chemical species largely due to the participation of its excited 3P (2s12p1) state as shown in the cases of Be2 and Be3. BeF- is a stable (D0 ≥ 81.4 kcal/mol) closed shell molecule that has been studied experimentally quite recently. Although it dissociates adiabatically to two closed shell atoms, Be (1S) and F-(1S), the bonding is due to the excited 3P (2s12p1) and 1D (2p2) Be states. © Copyright 2018 American Chemical Society