Abstract

The thermodynamic and other molecular properties found in the gas-phase database are all obtained from Bond Additivity Correction (BAC) calculations, a class of quantum-chemistry based methods developed by C.F. Melius, in collaboration with P. Ho and M.D. Allendorf, and described in detail in various publications. The BAC methods are based on the assumption that errors in electronic energies obtained from ab initio calculations are due to the finite size of the basis sets used and the application of limited electron correlation in the calculations. These errors are therefore systematic and can be corrected to achieve much greater accuracy for predicted heats of formation by applying a variety of empirical corrections related to the elements and bonds in the molecule.

The BAC suite of methods currently comprises several levels of theory. The most widely applied is the BAC-MP4 method, which was developed first. In this method, the molecular electronic energy is obtained from an ab initio electronic-structure calculation at the level of fourth-order Moller-Plesset perturbation theory. Methods using second-order Moller-Plesset perturbation theory (BAC-MP2), G2 theory (BAC-G2), and a hybrid method involving both density functional theory and MP2 have also been developed; these use a different approach for determining the empirical corrections to the ab initio electronic energy than the original BAC-MP4 method.

Full description of the Bond Additivity Correction (BAC) Calculations available (PDF Doc -- Adobe Acrobat required).

Content Comments to Mark Allendorf Site Comments to Michelle Medlin Last Modified on Oct 9, 2009	Site Maintained at Sandia National Laboratories for the US Department of Energy (DOE)