%0 Journal Article
%T Potential Energy Surfaces for Reactions of X Metal Atoms (X = Cu, Zn, Cd, Ga, Al, Au, or Hg) with YH4 Molecules (Y = C, Si, or Ge) and Transition Probabilities at Avoided Crossings in Some Cases
%A Octavio Novaro
%A Mar赤a del Alba Pacheco-Blas
%A Juan Horacio Pacheco-S芍nchez
%J Advances in Physical Chemistry
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/720197
%X We review ab initio studies based on quantum mechanics on the most important mechanisms of reaction leading to the C每H, Si每H, and Ge每H bond breaking of methane, silane, and germane, respectively, by a metal atom in the lowest states in symmetry: X(2nd excited state, 1st excited state and ground state) + YH4 H3XYH H + XYH3 and XH + YH3. with X = Au, Zn, Cd, Hg, Al, and G, and Y = C, Si, and Ge. Important issues considered here are (a) the role that the occupation of the d-, s-, or p-shells of the metal atom plays in the interactions with a methane or silane or germane molecule, (b) the role of either singlet or doublet excited states of metals on the reaction barriers, and (c) the role of transition probabilities for different families of reacting metals with these gases, using the H每X每Y angle as a reaction coordinate. The breaking of the Y每H bond of YH4 is useful in the production of amorphous hydrogenated films, necessary in several fields of industry. 1. Introduction Here, an overview of potential energy surface (PES) calculations for reactions of a metal atom with a gas molecule has been compiled. Among metal atoms, we consider cadmium, copper, zinc, gallium, aluminum, mercury, and gold, and among gas molecules methane, silane, and germane. The potential energy surfaces of an YH4 molecule with a metal atom were determined using ab initio Hartree-Fock Self-Consistent Field (HF-SCF) calculations, where the atom core is represented by relativistic effective core potentials (RECPs) [1每5]. These calculations are followed by a Multiconfigurational Self Consistent Field (MC-SCF) study [6]. The correlation energy is accounted for through extensive variational and perturbative second-order multireference Moller-Plesset configuration interaction (MR-CI) analysis of selected perturbations obtained by iterative process calculations using the CIPSI program package [7]. The reference (S) spaces used for the variational CI of the molecular states arising from the three X + CH4 asymptotes contain between 108 and 428 determinants, which generate between 7 million and 111 million perturbed MP2 determinants near the region of the reactants and the equilibrium geometry of the methyl-metal-hydride intermediate, respectively. This methodology is particularly useful in the study of systems constituted by a few atoms. Transition probabilities for the interaction of the lowest excited states of the metal X with tetrahedral gas molecules are studied through one-dimensional Landau-Zener theory. The strategy for obtaining the reaction pathways for X + YH4 interactions has been
%U http://www.hindawi.com/journals/apc/2012/720197/