个人简介

Ph.D., California Institute of Technology

研究领域

Theoretical characterization of reaction mechanisms in homogeneous and heterogeneous catalysis/new electronic structure techniques/development of force fields or model potentials for chemical reactivity studies.

Research interests are focused on the theoretical study of catalytic processes. Reactions currently under study include single-site propylene polymerization and hydrocarbon oxygenation. Modern Heterogenous catalysts function at the nanoscale with metal particles in the 10 nm range and metal sulfides with 3-5 nm wafer size. A particularly important question in catalysis is at what size do desirable bulk properties develop? When does a molecule become a solid? For properties such as ionization potential the bulk value is attained rather soon. The electron affinity and associated work function (IP-EA)/2 evolve more slowly, likely requiring hundreds of atoms. A catalytically important property that we are focussed on is the size-development of the solid-vacuum dielectric discontinuity which is present in a solid but absent in a molecular scale cluster. The associated electric field gradient likely plays an important role in stabilizing ionic species such as carbocations on catalyst particle surfaces. Since catalytic processes involve the reaction of relatively large chemical reagents in the condensed state, we, by necessity, are in the business of developing theoretical methodologies as well as validating and applying present-day techniques to catalytic reactions. This effort includes the development of molecular mechanics and dynamics technologies including the development of full periodic table molecular mechanics force fields, the development of functional forms and models consistent with the making and breaking of chemical bonds, and the development and documentation of molecular dynamics procedures for studying reactive species under controlled-temperature and high-pressure conditions. Since molecular mechanics and dynamics procedures, by their empirical nature, provide little insight into the electronic structure of metal ligand bonds and the electronic structural reorganization that accompanies a chemical reaction, we also utilize ab initio electronic structure tools. The types of electronic structure methods utilized generally attempt to include electron correlation (many-body) effects well enough to obtain reasonably accurate descriptions of the ground states of molecules both near equilibrium geometries and as they react. Additionally, correlation is included in a manner so as to permit interpretation and generalization of the electronic structural results into viable chemical concepts. These electronic structure techniques are used to probe the electronic control of catalytic processes through ligand tuning and to understand the character of metal ligand (primarily oxygen) bonding. Important questions here are 1) why do particular metal oxides epoxide olefins, others cis-dihdyroxylate olefins, and still others allylically oxidize olefins? 2) Can over oxygenation (combustion) be shut down by turning off radical autoxidation?

近期论文

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The effective continuum properties of a carbon sheet. Heyliger, P.H.; Rappe', A. K., Ramireza,F.; Karspeck, J. Phys. Rev. B, submitted. Mechanism of Chromyl Chloride Alkane Oxidation. Rappe', A. K., Jaworska M, J. Am. Chem. Soc. 125, ASAP (2003). Mechanism of Chromyl Chloride Epoxidation. Rappe', A. K., Li, S. J. Am. Chem. Soc. 125, 11168 (2003). Ab Initio Calculation of Nonbonded Interactions: Are We There Yet? Rappe' A. K.; Bernstein, E. R. J. Phys. Chem. 104, 6117-6128 (2000). Modeling Metal Catalyzed Olefin Polymerization. Rappe', A. K.; Skiff, W. M.; Casewit, C. J. Chem. Rev. 200, 1435-1456 (2000). LReO3 Epoxidizes, cis-Dihydroxylates, and Cleaves Alkenes as Well as Alkenylates Aldehydes: Towards an Understanding of Why. M. A. Pietsch, T. V. Russo, R. B. Murphy, R. L. Martin, and A. K. Rappe'. Organometallics, 17, 2716 (1998). Pi-Stacking Interactions: Alive and Well in Proteins. G. B. McGaughey, M. Gagne', A. K. Rappe'. J. Bio. Chem., 273, 15458 (1998). RFF, Conceptual Development of a Full Periodic Table Force Field for Studying Reaction Potential Surfaces. A. K. Rappe', M. A. Pietsch, D. C. Wiser, J. R. Hart, L. M. Bormann, and W. M. Skiff. J. Molecular Engineering, 7, 385 (1997). Evidence for a Ring Opening Preequilibrium in the Exchange Reactions of Diosmacyclobutanes, B. R. Bender, D. L. Ramage, J. R. Norton, D. C. Wiser, and A. K. Rappe'. J. Am. Chem. Soc., 119, 5628 (1997). Calorimetric Determination of Differential Heats of Solutions for a Set of Diastereomeric Salt Pairs. Z. Buday, A. K. Rappe', and T. G. Lenz. Chirality, 9, 325 (1997). Toward an Understanding of Zeolite Y as a Cracking Catalyst with the Use of Periodic Charge Equilibration. S. Ramachandran, T. G. Lenz, W. M. Skiff, and A. K. Rappe'. J. Phys. Chem. 100, 5898 (1996). Pi-Stacking as a Control Element in Elastomeric Polypropylene formation. M. A. Pietsch and A. K. Rappe'. J. Am. Chem. Soc. 118, 10908 (1996). Measurement of the Pyroelectric Effect for a Diastereomeric Salt Pair. Z. Buday, A. K. Rappe', and T. G. Lenz. Chirality, submitted. Vibrational Frequencies of Transition Metal Chloride and Oxo Compounds Using Effective Core Potential Analytic Second Derivatives. T. V. Russo, R. L. Martin, P. J. Hay, and A. K. Rappe'. J. Chem. Phys. 102, 9315 (1995). Predicted Structure Selectivity Trends: Substituted rac-(1,2ethylenebis(eta5-indenyl))Zr(IV) Catalysts. J. R. Hart and A. K. Rappe'. J. Am. Chem. Soc., 115, 6159 (1993). Application of a Universal Force Field to Metallic Complexes. A. K. Rappe', K. S. Colwell, and C. J. Casewit. Inorg. Chem., 32, 3438 Theoretical Modeling of the Mechanism of Dioxygen Activation and Evolution by Tetranuclear Manganese complexes. D. M. Proserpio, A. K. Rappe', and S. M. Gorun. Inorg. Chim. Acta, 213, 319 (1993). van der Waals Functional Forms for Molecular Simulations. J. R. Hart and A. K. Rappe'. J. Chem. Phys., 97, 1109 (1992). UFF, a Rule-Based Full Periodic Table Force Field for Molecular Mechanics and Molecular Dynamics Simulations. A. K. Rappe', C. J. Casewit, K. S. Colwell, W. A. Goddard III, and W. M. Skiff. J. Am. Chem. Soc, 114, 10024 (1992). Application of a Universal Force Field to Organic Molecules. C. J. Casewit, K. S. Colwell, and A. K. Rappe'. J. Am. Chem. Soc, 114, 10035 Application of a Universal Force Field to Main Group Compounds. C. J. Casewit, K. S. Colwell, and A. K. Rappe'. J. Am. Chem. Soc, 114, 10046 (1992). Sigma Bond Metathesis Reactions Involving Group 3 and 13 Metals. Cl2MH plus H2 and Cl2MCH3 plus CH4, M=Al and Sc. A. K. Rappe' and T. H. Upton. J. Am. Chem. Soc., 114, 7507 (1992). The Structure of Os(CO)4(C2H4), an Osmacyclopropane. B. R. Bender, J. R. Norton, M. M. Miller, O. P. Anderson, and A. K. Rappe'. Organometallics, 11, 3427 (1992).