AVS 47th International Symposium
    Surface Science Tuesday Sessions
       Session SS3+MC-TuM

Paper SS3+MC-TuM3
The KMLYP Density Functional Approximation: A New Method for Accurate Prediction of Activation Barriers and Enthalpies of Reaction

Tuesday, October 3, 2000, 9:00 am, Room 210

Session: Technique Innovations: Experiment, Theory and Simulation
Presenter: C.B. Musgrave, Stanford University
Authors: J.K. Kang, Stanford University
C.B. Musgrave, Stanford University
Correspondent: Click to Email
We develop the KMLYP hybrid DFT method which is shown to predict activation energies and enthalpies of reaction with smaller errors than B3LYP, G2, QCISD(T), CCSD(T), and CBS-APNO. The accuracy of the method is demonstrated on over 100 reactions. The KMLY P exchange functional is a hybrid functional that combines Hartree-Fock exact exchange with Slater exchange. The correlation functional is a hybrid functional combining Lee-Yang-Parr (LYP) correlation and Vosko-Wilk-Nusair (VWN) correlation. For reactions with reliable experimental data, the RMS deviation of the activation energies are 0.64 kcal/mol, 1.59 kcal/mol, 3.20 kcal/mol, and 3.10 kcal/mol for the KMLYP, CBS-APNO, G2, and B3LYP methods, respectively. The RMS deviations from experiment of the entha lpy of reaction are 1.57 kcal/mol, 2.24 kcal/mol, and 2.87 kcal/mol for the KMLYP, G2 and B3LYP methods, respectively. The KMLYP maximum absolute deviation of the activation barriers is 1.2 kcal/mol while the KMLYP maximum absolute deviation of the enthalpy of reactions is 3.8 kcal/mol. Furthermore, KMLYP is significantly more efficient than the G2, QCISD(T), CCSD(T), and CBS-APNO methods and is practical for the simulation of surface reactions using relatively large clusters.