Simulation Methods for Complicated Polymer Networks

Molecular simulations have boomed in recent years for natural macromolecules such as proteins, nucleic acids and polysaccharides. Different sets of molecular force fields, such as CHARMM, AMBER, OPLS and GROMOS etc. have been developed for such bio-related systems aiming at accurate prediction of molecular motions in the microscopic world. Albeit great progress in these natural systems, the simulations of synthetic polymers are fairly limited. Up to now, even a general force field describing most synthetic polymers is scarcely seen because of their greater varieties of the repeat units. Worse still, the most important category of synthetic polymers has network structure with random cross-links between chains of different length. Such complicated network polymers are clearly beyond the capability of classical quantum chemistry or the reactive force field methods. Normal simulations can only be limited to polymers with welldefined structures, and new methods for the generation of random network polymer structures are necessary.