Multi-coefficient Gaussian-3 method for calculating potential energy surfaces

We propose a multi-coefficient modification (MCG3) of the Gaussian-3 (G3) electronic structure method that is suitable for calculating continuous potential energy surfaces. We tested it for atomization energies and found that it improves the accuracy by 8% as compared to G3 and reduces the cost of single-point energy calculations by 50%. The method should be useful for calculating bond energies, potential energy surfaces, and thermochemical data of molecules.