Development of global potential energy surfaces for hydrocarbons up to C2H5+

PHYS 433

Bastiaan J. Braams, braams@mathcs.emory.edu1, Chao Chen2, Xinchuan Huang2, Zhong Jin2, Zhen Xie2, Xiubin Zhang2, Joel M. Bowman, jmbowma@emory.edu2, Amit Raj Sharma3, and Ralf Schneider3. (1) Department of Mathematics and Computer Science and Cherry L. Emerson Center for Scientific Computation, Emory University, Mathematics and Science Center #W401, 400 Dowman Drive, Atlanta, GA 30322, (2) Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, GA 30322, (3) Max Planck Institute for Plasma Physics, Greifswald, Germany
In connection with studies of combustion, spectroscopy, and interstellar chemistry we have constructed global potential energy surfaces for a variety of small hydrocarbons. The surfaces are invariant under permutations of like nuclei and the relevant dissociation behavior is built in by use of a many-body expansion. With a view also towards plasma chemistry and breakdown of methane and ethene in plasma we are currently extending this work to higher energy than before and to a systematic collection covering all small hydrocarbons up to C2H5; neutral and once charged; singlet, doublet, and triplet. These surfaces are based on least-squares fitting to a large number of ab initio calculations at the RCCSD(T) level of theory on an aug-cc-pvtz basis supplemented by MP4 on the same basis, using the Molpro 2002 program. Behind these fitted surfaces is the theory of invariants of finite groups and its implementation in the MAGMA computer algebra system, which allowed us to extend to much larger systems an approach that for 3-body and 4-body systems has a long history, e.g. [J. N. Murrell et al. Molecular Potential Energy Functions, Wiley, 1984]. Work supported by NSF-ITR CHE-0219331 and by ONR/DURIP.
 

Physical Chemistry Poster Session
7:30 PM-10:00 PM, Wednesday, 29 March 2006 Georgia World Congress Center -- Ex. Hall B4, Poster

Sci-Mix
8:00 PM-10:00 PM, Monday, 27 March 2006 Georgia World Congress Center -- Ex. Hall B4, Sci-Mix

Division of Physical Chemistry

The 231st ACS National Meeting, Atlanta, GA, March 26-30, 2006