Abstract

Nonlinear optical spectroscopy has opened the possibility of testing for unusually long-lived, non-dispersive Davydov soliton states in proteins. The Davydov soliton is a self-trapped vibrational excitation of an Amide I stretch in a protein helix that has its dynamics modulated by the hydrogen bonding network of the protein. The theory of Davydov solitons largely has been been studied using semi-classical techniques that invoke an adiabatic approximation. Here, we use mixed classical/quantum surface hopping simulations to study the time dependence of an excitation of a C=O vibration on a 3–10 helix of alpha-aminoisobutyric acid (AIB), a system which represents a test case for the formation of self-trapped states on a protein helix. We test for the soliton formation under conditions that include important features of a true biological system- 300K temperature, a solvent, hydrogen bond breaking and reforming.

© 2010 Optical Society of America