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Condensed Matter and Statistical Physics Journal Club

Date: September 15, 2008
Title: Failure of the work-Hamiltonian connection for free-energy calculations
Speaker: Malay Bandyopadhyay
Reference: "Failure of the Work-Hamiltonian Connection for Free-Energy Calculations" by Jose M. G. Vilar and J. Miguel Rubi [Phys.Rev.Lett., arXiv:cond-mat.stat-mech]
Abstract: "Extensions of statistical mechanics are routinely being used to infer free energies from the work performed over single-molecule nonequilibrium trajectories. A key element of this approach is the ubiquitous expression dW/dt = ∂H ( x, t )/∂t, which connects the microscopic work W performed by a time-dependent force on the coordinate x with the corresponding Hamiltonian H(x,t) at time t. It is shown that the above mentioned connection cannot be used to estimate free-energy changes. The implications of this result for single-molecule experiments and atomistic molecular simulations are discussed and possible avenues to overcome these limitations has been pointed out."