Helical polymer circular dichroism: Transition matrix theory for polypeptides

摘要

A Green operator technique used within a linear response framework is employed to present a transition matrix theory of long helical polymer circular dichroism. Specializing to a polypeptide, simple closed form expressions are obtained for the circular dichroism. The formulation clearly shows (1) how the Pgr;Pgr;ast; exciton system gives rise to the rsquo;rsquo;helix bandrsquo;rsquo; and rsquo;rsquo;radial bandsrsquo;rsquo;; (2) how the coupling of the Pgr;Pgr;ast; andnPgr;ast; transition densities gives rise to a band centered at the unperturbednPgr;ast; transition frequency which is balanced in rotational strength by bands at the Pgr;Pgr;ast; perpendicular and parallel polarized transition frequencies; and (3) how interaction of these low energy transitions with high energy transitions can alter all of the above mentioned bands.