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Quantum Chemical Studies of Chemical Reactivity

Carlos A. Gonzalez         Research Opportunity Number 50.63.21.B4054

This research uses a wide range of Quantum Chemical methods in the computation of the energetics and mechanisms governing complicated chemical reactions. The use of ab initio electronic structure methodologies to study such problems has become very popular during the past five years mainly due to the availability of powerful hardware and the development of more efficient algorithms. Despite this success, the routine application of such methods is still limited to problems containing at most, an average of 50 atoms. Recently, there has been an increased interest in alternative methods such as Density Functional Theory ( DFT) and Semi-Empirical Molecular Orbital Theory (SEMOT) that are considerably less computationally demanding. Given the empirical nature of their implementations, these methodologies are not robust enough to consistently predict reactivity and chemical properties with a reasonable degree of accuracy even within the same class of reactions. We are interested in the development and calibration of new DFT functionals as well as new SEMOT Hamiltonians that could reliably be used to predict energetics and molecular properties. Preliminary work leading to the developing of new DFT functionals that could be used in the prediction of reaction barriers and reaction rate constants has started. Another area of research involves the development and implementation of efficient algorithms for the characterization of potential energy surfaces governing complicated chemical systems. So far, a state-of-the-art computer program that uses novel algorithms to locate minima, transition states, and minimum reaction paths has been implemented. Kinetics modules are being developed and will be integrated into the software soon. We have access to an IBM SP2 with 37 nodes, several IBM/RS6000 workstations, and an SGI Origin 2000 with 8 processors. Computational packages such as GAUSSIAN 98, GAMESS-US, MOLPRO 96, HONDO 8.1, MOLCAS, MOLFDIR, and ACES-II are also available.