The paper by Hammer, Hansen, and Nørskov investigates the improvement of adsorption energetics within density-functional theory (DFT) using revised Perdew-Burke-Ernzerhof (PBE) functionals. The authors show that the Zhang and Yang revision of the PBE functional (revPBE) significantly improves the chemisorption energies of atoms and molecules on transition-metal surfaces. They test this on systems such as atomic and molecular adsorption of oxygen, CO, and NO on Ni(100), Ni(111), Rh(100), Pd(100), and Pd(111) surfaces. The revPBE functional deviates from the PBE functional by changing one parameter, κ, from 0.804 to 1.245, which improves the description of atomic total energies and molecular atomization energies. However, the revPBE functional locally violates the Lieb-Oxford criterion, which is a requirement for the construction of GGA functionals. To address this issue, the authors develop an alternative revision of the PBE functional, RPBE, which gives the same improvement in chemisorption energies as the revPBE functional while fulfilling the Lieb-Oxford criterion. The RPBE functional is constructed by modifying the functional form of the exchange energy enhancement factor \( F_X(s) \) in the PBE functional. The results show that both the revPBE and RPBE functionals provide accurate descriptions of chemisorption energies, with rms deviations of around 0.3 eV for O, CO, and NO adsorption. The paper also discusses the physical reasons behind the improvement in chemisorption energies and the limitations of the LDA functional, which overbinds by about 1.5 eV per adsorbate.The paper by Hammer, Hansen, and Nørskov investigates the improvement of adsorption energetics within density-functional theory (DFT) using revised Perdew-Burke-Ernzerhof (PBE) functionals. The authors show that the Zhang and Yang revision of the PBE functional (revPBE) significantly improves the chemisorption energies of atoms and molecules on transition-metal surfaces. They test this on systems such as atomic and molecular adsorption of oxygen, CO, and NO on Ni(100), Ni(111), Rh(100), Pd(100), and Pd(111) surfaces. The revPBE functional deviates from the PBE functional by changing one parameter, κ, from 0.804 to 1.245, which improves the description of atomic total energies and molecular atomization energies. However, the revPBE functional locally violates the Lieb-Oxford criterion, which is a requirement for the construction of GGA functionals. To address this issue, the authors develop an alternative revision of the PBE functional, RPBE, which gives the same improvement in chemisorption energies as the revPBE functional while fulfilling the Lieb-Oxford criterion. The RPBE functional is constructed by modifying the functional form of the exchange energy enhancement factor \( F_X(s) \) in the PBE functional. The results show that both the revPBE and RPBE functionals provide accurate descriptions of chemisorption energies, with rms deviations of around 0.3 eV for O, CO, and NO adsorption. The paper also discusses the physical reasons behind the improvement in chemisorption energies and the limitations of the LDA functional, which overbinds by about 1.5 eV per adsorbate.