Thermal length fluctuations of a linear chain of masses connected by springs in a viscous medium

Abstract

By applying the Fluctuation Dissipation Theorem the root mean-square amplitude (RMSA) of the longitudinal vibrations of a linear chain of masses connected by springs in a viscous medium is estimated as a function of the mass of the particles, the force constant of the springs, the number of particles, the damping parameter and temperature. At room temperature the RMS end-to-end length is found to vary from a few tenths of an Angström for hydrocarbon chains of the length found in phospholipid membrane bilayers to several Angströms in α-helices of peptide residues.