Merck molecular force field (MMFF) is a family of chemistry force fields developed by Merck Research Laboratories. They are based on the MM3 force field. MMFF is not optimized for one use, such as simulating proteins or small molecules, but tries to perform well for a wide range of organic chemistry calculations. The parameters in the force field have been derived from computational data consisting of approximately 2800 structures spanning a wide range of chemical classes