Electronic Structure of Vanadium Oxide. Neutral and Charged Species, VO^0,±

Abstract

The diatomic molecule vanadium oxide, VO, and its charged species VO+ and VO- were studied by multireference and coupled cluster methods in conjunction with large basis sets. The investigation of 22 states and the construction of 21 full potential energy curves allowed for a detailed understanding of the electronic structure of these species. Our best binding energies for the ground states of VO (X4Sigma-), VO+ (X3Sigma-), and VO- (X3Sigma-) were De = 150, 138, and 143 kcal/mol, respectively, in harmony with the corresponding experimental values. For both species VO and VO+ and for all states studied, the bonding showed a strong ionic character conforming to the models V+O- and V2+O-.

ExoMol line lists – XVIII. The high-temperature spectrum of VO

“…A good summary of previous experimental results is given by Miliordos & Mavridis (2007) and Hopkins et al (2009). Generally, only the ground and first vibrational energy levels are well characterised for observed electronic states.…”

“…We use some of the Miliordos & Mavridis (2007) results for potential energy curves as a source of data for our line list. In particular, we use their results to fit the potential energy curves of the a 2 Σ − and b 2 Γ states and also use their calculation of the diagonal spin-orbit splitting of the c 2 ∆ and e 2 Φ state to fix the spin-orbit splitting of the c 2 ∆, e 2 Φ and f 2 Π states (the relative size of the spin-orbit coupling is known from experiment, but not their absolute values).…”

“…In particular, we use their results to fit the potential energy curves of the a 2 Σ − and b 2 Γ states and also use their calculation of the diagonal spin-orbit splitting of the c 2 ∆ and e 2 Φ state to fix the spin-orbit splitting of the c 2 ∆, e 2 Φ and f 2 Π states (the relative size of the spin-orbit coupling is known from experiment, but not their absolute values). However, Miliordos & Mavridis (2007) did not consider dipole moment (diagonal or off-diagonal), spin-orbit or electronic angular momentum coupling curves. New calculations for these properties are presented here.…”

“…The λ parameter controls the distance between the two diabatic states and their crossing points and is of the form λ = m(R − d)(R − k), where k and d are the crossing points of the ionic and covalent diabatic curves (assuming that the ionic curve is a quadratic function of energy and the covalent curve is a linear or constant function) and m together with j controls the depth of the ionic well. We constrain k =2.75Å ; this is the predicted location of the avoided crossing of the X 4 Σ − state (Miliordos & Mavridis 2007). Physically, d is approximately the short bond length where the energy of the harmonic potential of the ionic state equals the energy of the covalent state (which is to a first approximation the dissociation energy); this was constrained to d = 1Å without significantly affecting the quality of the fit.…”

“…The most detailed ab initio electronic structure study was performed by Miliordos & Mavridis (2007), who looked at the lowest nine electronic states, and also reviewed previous theoretical studies. The quality of these calculations is high, but quantitative results are only given for equilibrium values.…”