Computer simulations on polysilanes: A new method for modeling the energetics and dynamics of their thermochromic transitions

Publisher Website
Google Scholar
Abstract
The present article summarizes the author's recent work on the computer‐based molecular modeling of polysilanes [‐SiR2‐]. First, conformational energies were calculated by molecular mechanics on model compounds for poly(dimethylsilane) (PDMS), poly(diethylsilane) (PDES), and poly(di‐n‐hexylsilane) (PDHS). Discrepancies in conformational preferences between calculated and experimental results are attributed to factors not accounted for in these calculations, such as electronic stabilization and packing forces. Second, molecular dynamics simulations carried out on a model compound for PDHS suggest the presence of an abrupt “gas phase” thermochromic transition, analogous to the abrupt thermochromic transitions observed for PDHS both in solution and in the solid state. Third, we develop a methodology for testing Schweizer's theory of polysilane thermochromism based on the existence of a unique polymer‐solvent conformation‐dependent stabilization energy present in conjugated chains. In his treatment of the polysilanes, Schweizer adopted reasonable estimated values for this stabilization energy term VD. Presented here is a derivation of an analytical expression for VD based on a first‐principles approach. © 1993 by John Wiley & Sons, Inc.