Calculated effect of propeller twist in a DNA polymer on its absorption in the far-infrared region

Abstract
A base pair in DNA comprises two ringed planar structures joined together by hydrogen bonds. The opposite rotation of these two structures about their lengthwise axis is referred to as propeller twist. We examine the effect of propeller twist on our calculation of the far-infrared absorption in a homopolymer DNA, specifically, B poly(dA)-poly(dT). In our previous calculation [Phys. Rev. A 39, 3173 (1989)], we found agreement with experimental infrared data except for one mode. We now give evidence that this mode may be due to the propeller-twist conformation.