Calculation of Cluster-free Energies Using the Jarzynski Relation
Knowledge of the free energy of formation of molecular clusters, based on a microscopic model of the intermolecular interactions, forms the basis of the theoretical understanding of aerosol nucleation. A number of methods have been developed to calculate this quantity, but most are rather time consuming. As an alternative, we have sought to exploit the Jarzynski relation, which is a powerful result in nonequilibrium statistical physics, connecting a free energy change to the mechanical work associated with the change. Thus we plan to pull a cluster apart with external forces over the course of a molecular dynamics simulation and use the Jarzynski relation to evaluate the associated free energy of formation, or rather disassembly. As a first step we have tested the procedure on the separation of a dimer.
Keywords Homogeneous nucleation, free energy
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