Theoretical study of the reaction of H2 with a Cu2Pt2 cluster

Abstract

The study of the interaction of a pyramidal tetramer of Cu2Pt2 with the H2 is reported here through ab initio multiconfigurational self-consistent field (MC-SCF) calculations, plus extensive multireference configuration interaction (MR-CI), variational and perturbative calculations. The lowest three electronic states X 1A′, a 3A′ and a 1A′ of the bare cluster were considered in order to study this interaction. For the H2 Cs approaching a Pt vertex, results show that the Cu2Pt2 pyramid cluster in its X 1A′ and a 1A′ states can spontaneously capture and dissociate the H2. For the H2 Cs approaching a Cu vertex, where H2 is located in the Cs reflecting plane, the Cu2Pt2 cluster in its X 1A′ electronic state shows capture of the hydrogen molecule after surmounting an energy barrier; moreover, in this approach the Cu2Pt2 cluster in its a 1A′ electronic state shows spontaneous capture of the hydrogen molecule. For the H2 approaching a Cu vertex, where the Cs reflecting plane bisects the H2 molecule, the Cu2Pt2 cluster in its three lowest-lying states is able to capture the hydrogen molecule after surmounting a small barrier. The Cu2Pt2+H2 Cs face-on interactions show a lower H2 activation than that which was obtained in the equivalent Pt4+H2 interactions.