The reason for these faster calculations is that force fields are parametrized based on the Gibbs free energies determined after optimization of each molecule. These correlations could be improved by identifying a better extended parametrization for the Maestro's cutoff potential options that considers the van der Waals, electrostatics, and hydrogen bonding interactions which have been well studies and reported in the literature. Moreover, since each force field has a particular training set, the nature of the training set must be considered. For example, OPLS and OPLS3e are force fields preferred for biopolymers and carbohydrates, whereas OPLS2005 is the preferred force field for biological systems and organic molecules. This could explain the higher correlation coefficient obtained with OPLS2005. optimized using B3LYP/6-31G(d). This is an example of a case in which higher energy structures (left) yield better results than lower energy structures (right).