Calculating Interaction Energies Using First Principle Theories: Consideration of Basis Set Superposition Error and Fragment Relaxation

J. Phillip Bowen

Center for Drug Discovery, Department of Chemistry and Biochemistry, University of North Corolina at Greensboro, Greensboro, NC 27402

Jennifer B. Sorensen

Department of Chemsitry, Seattle University, Seattle WA 98122

Karl N. Kirschner

Department of Chemistry, Center for Molecular Design, Hamilton College, Clinton, NY 13323

Abstract

The use of computational chemistry tools has become prevalent in a wide variety of research areas. Many researchers are using computational chemistry as an additional tool to explore and gain insight into the problems they are researching. As such it is important to educate future scientists in the capabilities and proper implementation of theoretical tools. In this article we explain a difficult aspect of computational chemistry: calculating accurate interaction energy by correcting for basis set superposition error and fragment relaxation. There are four fundamental methods to calculate an interaction energy using ab initio theory, two of which take into account basis set superposition error. Using the methanol–water complex as a model, we demonstrate how to calculate an interaction energy using these four different methods. Additionally, we perform a comparison of the interaction energies and examine the magnitude of basis set superposition error as a function of basis set size. Fragment relaxation will be discussed in relation to these methods and is an indication of the magnitude of the inductive forces for each monomer.

Journal of Chemical Education 2007, 84, 1225                  Full Text (PDF)

-- ThanhTruong - 11 Jul 2007