Energy transport by lattice solitons in α-helical proteins

Yomosa’s model for peptide chains is generalized in two respects. (1) The internal vibrations of the peptide groups are incorporated by considering a one-dimensional lattice with alternating masses and alternating linear and nonlinear interactions for the intrapeptide bonds and the hydrogen bonds between the peptide groups, respectively. (2) Discreteness effects are taken into account by applying a new version of Collin’s quasicontinuum approach. In the cases in which this approach is not sufficient, we apply an iterative method where the accuracy can be increased systematically. We obtain very narrow solitons with lower and upper velocity limits. Our results have been confirmed by computer simulations. The lifetime of the solitons is finite due to the emission of optical phonons. However, using α-helix parameters, this effect is negligible.