Molecules as in a thermal bath exhibit fluctuations of amplitude that increases as T1/2. Macroscopic systems in contact with a single bath at fixed temperature are forbidden from perpetual oscillation by the Second Law. Mesoscopic systems are shown here to be capable of supporting perpetual oscillatory deformation about equilibrium, and with amplitude that decreases with T beyond a critical T-value. This phenomenon is demonstrated via all-atom simulation for an icosahedral T=1 assembly of 60 human papillomavirus proteins in an aqueous environment. The oscillations period is on the order of 60 ps, while the peak to peak amplitude is roughly 4� at 300K, pH 7, and ionic strength 0.25M. The assembly is organized into 12 pentamers in a T=1 icosahedral structure and the oscillatory dynamic consists of a complex pattern of centrifugal pentamer displacements. These displacements are out-of-phase for neighboring pentamers (i.e. inward versus outward). The oscillatory dynamic emerges via the interplay of free energy landscape topography and omnipresent fluctuations. There are other cases where Second Law violation is apparent, but they do not display perpetual coherent oscillatory motion. These results are based on both conventional and multiscale Molecular Dynamics. The latter follows from a mathematical formalism wherein Langevin-type equations are derived for coarse-grained variables starting with the N-atom Newtonian equations. These Langevin equations are obtained in the non-inertial, friction-dominated limit, implying that the oscillations are not of the conserving, normal mode type. The multiscale and conventional MD simulations agree, underscoring the validity of the results. To further probe the phenomenon, near-resonant responses to infraterahertz oscillatory fields are shown computationally to be a promising direction. Conjectures on the implications of the phenomenon for molecular electronics, virus behavior, and other nanoscience applications are made.

Perpetual oscillatory motion in an isothermal mesoscopic system: Applications to nanotechnology

246th National Meeting (2013)

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