Improved adsorption energetics within density-functional theory using revised Perdew-Burke-Ernzerhof functionals

A simple formulation of a generalized gradient approximation for the exchan ge and correlation energy of electrons has been proposed by Perdew, Burke, and Ernzerhof (PBE) [Phys. Rev. Lett. 77, 3865 (1996)]. Subsequently Zhang and Yang [Phys. Rev. Lett. 80, 890 (1998)] have shown that a slight revisio n of the PBE functional systematically improves the atomization energies fo r a large database of small molecules. In the present work, we show that th e Zhang and Yang functional (revPBE) also improves the chemisorption energe tics of atoms and molecules on transition-metal surfaces. Our test systems comprise atomic and molecular adsorption of oxygen, CO, and NO on Ni(100), Ni(111), Rh(100), Pd(100), and Pd(111) surfaces. As the revPBE functional m ay locally violate the Lieb-Oxford criterion, we further develop an alterna tive revision of the PBE functional, RPBE, which gives the same improvement of the chemisorption energies as the revPBE functional at the same time as it fulfills the Lieb-Oxford criterion locally. [S0163-1829(99)02711-3].