Prediction of polymer crystal structures and properties

Abstract

The simulation of the packing of polymer molecules in crystals is, in a sense, computationally simple. The number of degrees of freedom to be considered is quite limited; they are comprised only of the atom coordinates of the repeat unit and the unit cell parameters. Energy minimization serves to define the structure and often yields very useful results. Computer strategies can be designed to allow simultaneous optimization of the internal molecular geometry and the crystal packing. A number of useful crystal properties can be calculated in addition to finding the structure. However, because the molecules can usually pack in a number of stable forms, the application actually can be far from simple. These various forms have to be discovered. The evaluation of their relative stability puts great demands on the quality of the empirical force field parameters.