STRUCTURE AND PROPERTIES OF POLYMERS CALCULATED BY AB-INITIO MOLECULAR-DYNAMICS

The Car-Parrinello ab initio molecular dynamics scheme combines electr onic structure calculations with complete geometry optimizations very efficiently. For the first time we apply this method to organic semico nducting polymers. Equilibrium geometries are calculated for a series of polymers: polythiophene (PTh), polypyrrole (PPy), polyisothianaphte ne (PITN), polyparaphenylene (PPP), polyaniline (PANI) and polyparaphe nylenesulfide (PPS). The bandgaps of these polymers, calculated with t he local density functional, are shown to correctly represent the tren d in the experimental optical bandgap.