9627786 Krimm The goal of this proposal is the application of a new form of potential energy function to the study of structure, spectra, and dynamics of polymeric macromolecules. The PIs have developed a method of transforming scaled ab initio force fields into molecular mechanics energy functions so that vibrational frequencies as well as structures and energies are preserved. An advantage of this so-called spectroscopically determined force field (SDFF) is that it permits reliable normal mode calculations to be made on different conformations of a macromolecule. In addition, because of its spectroscopic accuracy, it should result in more physically meaningful molecular dynamics simulations. The PIs have already implemented the SDFF approach for polyethylene, and shown that it leads to more accurate predictions of the elastic modulus of this polymer. This proposal extends this method to the development of SDFFs for other polymers, in particular branched systems, olefinic systems, and the nylons. The PIs have also developed an electrostatic model for the prediction of infrared band intensities, which will be incorporated with the SDFFs. Elastic moduli will be calculated for these polymers, as will molecular dynamics simulations of some of these systems. %%% The use of SDFFs in structural and spectroscopic studies of polymers can be expected to result in more reliable predictions of their physical properties. This will enhance the power of computational approaches in polymer science. ***
