Prediction of modes with dominant base roll and propeller twist in B-DNA poly(dA)-poly(dT)

In solving the secular equation of a one-dimensional infinite lattice model of poly(dA)-poly(dT), we obtain dispersion relations. [The notation poly(dA)-poly(dT) means that one strand contains only adenine (A) bases, and the other only thymine (T) bases.] We solve the equation for consecutive refinements of the nonbonded force constants based on Raman, Brillouin, and neutron scattering and Fourier-transform infrared experiments in both polynucleotides and random sequence DNA. When these eigenvectors are examined for base roll and propeller twist, such characteristics are found to be dominant in modes around 50 ${\mathrm{cm}}^{\mathrm{-}1}$.