SOLID-STATE POLYMERIZATION OF ACETYLENE UNDER PRESSURE - AB-INITIO SIMULATION

We have simulated by ab initio constant pressure molecular dynamics th e solid-state polymerization of acetylene recently observed experiment ally in the pressure range 3.5-14 GPa. We have found a massive polymer ization only at much higher pressure (25 GPa). However, we have also f ound that a triplet exciton self-trapped on a single, cis-bent molecul e in crystalline acetylene is a very effective polymerization seed at lower pressure (<9 GPa), much closer to the experimental threshold. Th erefore, we propose that the polymerization observed experimentally is possibly catalyzed by a similar seed. We predict that injection of tr iplet excitons would greatly enhance the polymerization rate.