Embodiments of the present invention provide, among other things, methods, apparatus, and systems for tuning a semiempirical process for predicting energy for different molecular configurations. In an example method, an energy value and an energy gradient are determined for each of a plurality of molecular configurations using an accurate method. A functional form of the semiempirical process is optimized using the determined energy values and energy gradients via multiobjective optimization. The functional form relates one or more parameters to energy values and energy gradients.