Molecular mechanics parameters development

My postdoctoral research at the University of Maryland Baltimore was focused on the development of CHARMM General Force Field (CGenFF) parameters for non-standard molecules like oxetane and metal-porphyrin systems. The bonded parameters and the corresponding force constants of oxetane and metal-porphyrin in CGenFF were optimized based on accurately reproducing the QM data which were obtained at the MP2/6–31G* and the B3LYP/6-31G*-LANL2DZ (Metal) level of theory respectively. Experimental pure solvent densities and heats of vaporization were used for optimization of LJ parameters for oxetane. Optimization of the partial atomic charge was performed based on reproducing the HF/6-31G* level interaction energies of query compounds with TIP3P water (Fig. 1) molecules. The Oxetane parameters are already incorporated in the current updated version of the CHARMM General Force Field (CGenFF) and the parameters of metal-porphyrin systems are under testing and will be added in the next release of CGenFF.

Figure 1: CGenFF parameterization scheme for small organic molecule and Interaction orientations of water molecules with Oxetane were used for charge optimization of this molecules during parameterization.