Multi-coefficient Correlation Method:  Comparison of Specific-Range Reaction Parameters to General Parameters for C<i>_n</i>H<i>_x</i>O<i>_y</i>Compounds

We optimized the coefficients for 11 multi-coefficient correlation methods (MCCMs) against 54 atomization energies for molecules composed of C, H, and O atoms and containing 343 bonds. The methods included two scaling-all-correlation (SAC) methods, a multi-coefficients SAC (MCSAC) method, three Utah methods, two Colorado methods, MC-QCISD, MCG3, and G3S. The mean unsigned errors are (on average) 36% lower than for calculations with general parameters. The mean unsigned error per bond for the most highly recommended methods is only 0.1−0.2 kcal/mol.