Electronic structure of the [MgO3]+ cation

Abstract

Accurate ab initio calculations are performed to investigate the stable isomers of [MgO(3)](+) and its lowest electronic states at both molecular and asymptotic regions. The calculations are done using large basis sets and configuration interaction methods including the complete active space self-consistent field, the internally contracted multi-reference configuration interaction, the standard coupled cluster (RCCSD(T)) approaches and the newly implemented explicitly correlated coupled cluster method (RCCSD(T)-F12). The presence of three stable forms is predicted: a cyclic global minimum c-MgO(3)(+), which is followed by a quasi-linear isomer, l2-MgO(3)(+). A third isomer of C(s) symmetry (l1-MgO(3)(+)) is also found. Moreover, we computed the one-dimensional cuts of the six-dimensional potential energy surfaces of the lowest doublet and quartet electronic states of [MgO(3)](+) along the R(MgO) and R(OO) stretching coordinates covering both the molecular and the asymptotic regions. These curves are used later for discussing the metastability of this cation and to propose plausible mechanisms for the Mg(+) + O(3) atmospherically important ion-molecule reaction and related reactive channels.

Characterization of the MgO2+dication in the gas phase: electronic states, spectroscopy and atmospheric implications

“…In 2008, Yazidi et al 14 investigated the corresponding reaction pathways. For reaction (2), Rowe et al 9 evaluated the rate constant to be 1 Â 10 À10 cm 3 s À1 at T = 300 K. Very recently, Ben Houria et al 15 showed that ionmolecule reactions between Mg and O 3 + may lead also to the formation of Mg + but in less extent because of the lower abundance of ozone in the atmosphere compared to O 2 and O. For reaction (4), the measured rate constant is 2.3 Â 10 À10 cm 3 s À1 (at T = 300 K).…”

Generation of full dimensional potential energy surfaces for atmospherically important charge transfer tetratomic complexes: the case of the OMgOO+ radical cation

“…[2][3][4] These species are involved in a multitude of neutral-neutral and ion-molecule reactions. Recent investigations 4,5 showed the formation of the MgO 3 and MgO 3 + tetratomic superoxides through the reactions of atomic Mg, MgO or MgO 2 molecules with O, O 2 or O 3 appropriate neutral or ionic partners. Specifically, Ben Houria et al 5 pointed out the crucial role of the OMgOO + complex cation during the reactive collisions between MgO/MgO + and O 2 + /O 2 ;…”

“…5 of ref. 5 shows the corresponding reaction path: the reactive collisions between Mg + + O 3 lead to the formation of the OMgOO + ( 2 A 0 , 2 A 00 ) ion that decomposes later to form MgO + + O 2 . Such reactions should influence the local and global concentrations of the neutral and ionic Mg, O 3 , O 2 species in the Earth's atmosphere.…”

“…The OMgOO + ion is the second most stable form of the MgO 3 + sum formula. 5 At the coupled cluster level of theory, Ben Houria et al established a X ˜4A 0 ground electronic state. This quartet is followed by a couple of doublet states ( 2 A 0 and 2 A 00 ) that correlate adiabatically with a 2 P state at linearity forming a Renner-Teller system.…”

“…These doublets and the quartet correlate adiabatically to the lowest dissociation limit {MgO + (X 2 P) + O 2 (X 3 S g À )}. 5 Both doublet and quartet states of OMgOO + are intermediates of the atmospherically important reaction between MgO + and O 2 (cf. Fig.…”