Multi-coefficient correlation method: Comparison of specific-range reaction parameters to general parameters for CnHxOy 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-cor relation (SAC) methods, a multi-coefficients SAC (MCSAC) method, three Utah methods, two Colorado methods, MC-QCISD, MCG3, and G3S. The mean unsigned errors are ton average) 36% lower than for calculations with general parame ters. The mean unsigned error per bond for the most highly recommended meth ods is only 0.1-0.2 kcal/mol.