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We provide an overview of the IMPACT molecular mechanics program with an emphasis on recent developments and a description of its current functionality. With respect to core molecular mechanics technologies we include a status report for the fixed charge and polarizable force fields that can be used with the program and illustrate how the force fields, when… (More)
A QM–MM method, using our previously developed frozen orbital QM–MM interface methodolgy, is presented as a general, accurate, and computationally efficient model for studying chemical problems in a protein environment. The method, its parametrization, and a preliminary application to modeling cytochrome P-450 chemistry are presented.
Protein effects in the activation of dioxygen by methane monooxygenase (MMO) were investigated by using combined QM/MM and broken-symmetry Density Functional Theory (DFT) methods. The effects of a novel empirical scheme recently developed by our group on the relative DFT energies of the various intermediates in the catalytic cycle are investigated.… (More)
Taking Pd di-imine catalysts as an example, we use first principles density functional theory (B3LYP/6-31G) to investigate the chain propagation steps for polymerization of polar monomers. We start with the complex formed from insertion of ethylene into the polymer chain and consider insertion into the Pd-C bond for each of four polar monomers: methyl… (More)
We consider the conformational flexibility of molecules and its implications for micro- and macro-pKa. The corresponding formulas are derived and discussed against the background of a comprehensive scientific and algorithmic description of the latest version of our computer program Jaguar pKa, a density functional theory-based pKa predictor, which is now… (More)
Since the advent of Ziegler-Natta polymerization of ethylene, attempts have been made to extend coordination polymerization to commercially important monomers with polar functionality. In this study we examined the copolymerization of perdeuterated vinyl chloride (VC) and perdeuterated vinyl acetate (VA) with ethylene using a tridentate Fe(II) dichloride… (More)