A bond energy bond order model for electronic energy

COMP 75

Sonia Tulyani, tulyans@utrc.utc.com, Department of Chemistry, Wesleyan University, Hall-Atwater Laboratories of Chemistry, Middletown, CT 06459-0180, George A. Petersson, gpetersson@wesleyan.edu, Chemistry Department, Wesleyan University, Hall-Atwater Laboratories of Chemistry, 237 Church Street, Middletown, CT 06459-0180, and Phillip R. Westmoreland, westm@ecs.umass.edu, Department of Chemical Engineering, University of Massachusetts Amherst, 159 Goessmann Lab, 686 N. Pleasant, Amherst, MA 01003-9303.
Bond energies are proportional to bond orders obtained from generalized valence bond (GVB) wave functions. Addition of an exponential repulsive term reproduces the potential energy curves of several diatomic molecules to within 1 kcal/mol. A semiempirical scheme based on GVB ab initio calculations would be impractical. However, the GVB bond orders are accurately reproduced by convolution of Hartree-Fock bond orders with a “Fermi-Dirac distribution” mapped onto the interval from RAB = 0 to RAB = ∞. The resulting bond order to bond energy “density functional” is: EAB ≈ BO(A,B)*BAB/{1 + exp[β(RAB/RF – RF/RAB)]}, where BAB, β, and RF are empirical parameters adjusted to fit ab initio energies. This functional can also be applied to bond orders obtained from B3LYP or LSDA wave functions. Application to modified extended Hückel bond orders provides a bond energy bond order potential (BEBOP) that can be generated rapidly enough to be used for reactive molecular dynamics.
 

Bold Predictions in Theoretical Chemistry: A Poster Session in Honor of One of the Boldest, Bill Goddard, on the Occasion of his 70th Birthday
7:30 PM-9:30 PM, Sunday, August 19, 2007 BCEC -- Exhibit Hall - B2, Poster

Division of Computers in Chemistry

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007