Kinetic Barriers of the Phase Transition in the Oxygen Chemisorbed Cu(110)-(2 x 1)-O as a Function of Oxygen Coverage

Oxygen chemisorption induced surface reconstructions are widely observed, but the atomic processes leading to transitions among oxygen chemisorbed phases are largely unknown. Using ab initio molecular dynamics and density-functional theory, we study the kinetic process of the Cu(110)-(2 x 1) -> c(6 x 2) phase transition upon increasing oxygen surface coverage. We show that the phase transition involves initially Cu-O dimer and Cu-O-Cu trimer formation with a kinetic barrier of similar to 0.13 eV, followed by a barrierless process of forming a four Cu-O-Cu-O chains configuration that transitions to the c(6 x 2) reconstruction via concerted movement of three Cu atoms with an associated energy barrier of similar to 1.41 eV. The larger kinetic barrier is suggested as the origin of the kinetic hindrance that is inferred from the significant discrepancy between the experimentally observed temperature and pressure dependent (2 x 1) -> c(6 x 2) phase transition and the equilibrium thermodynamics prediction.