Nonadiabatic quantum dynamics of the reversible oxidation of Cu₅ clusters

Nuclear quantum effects become significant for metal clusters consisting of a few atoms. We investigate the nonadiabatic quantum dynamics of the chemisorption of O₂ onto the trigonal bipyramidal Cu₅(O₂)₂ cluster. The two-dimensional diabatic potential energy surfaces were obtained directly from electronic structure calculations [A. O. Mitrushchenkov, A. Zanchet, A. W. Hauser and M. P. de Lara-Castells, J. Phys. Chem. A 125, 9143 (2021)]. We perform flux analysis of the split-operator quantum wavepacket dynamics to obtain the probability of the electron transfer reaction from the copper cluster to the incoming O₂. Boltzmann averaging gives the estimate of the temperature-dependent electron transfer probability. The nonadiabaticity of Cu₅(O₂)₂ + O₂ system contributes to its resistance to charge transfer. The semiclassical Landau-Zener theory qualitatively predicts the same trend as the one and two-dimensional quantum dynamics. Both higher energy barrier and smaller diabatic coupling of Cu₅(O₂)₂ + O₂ compared to those of bare Cu₅ + O₂ suppress the molecular oxidation. We demonstrate the importance of nonadiabatic effects in characterising nanometre-scale metal clusters.