Metadynamics is an established sampling method aimed at reconstructing the free-energy surface relative to a set of appropriately chosen collective variables. In Metadynamics the free-energy surface is filled by Gaussian potentials of preassigned and typically diagonal covariance. Asymptotically the free-energy surface is proportional to the bias deposited. We consider the possibility of using Gaussians whose variance is adjusted on the fly to the local properties of the free-energy surface. We suggest two different prescriptions, one based on the local diffusivity and the other on the local geometrical properties. We examine the problem of extracting the free-energy surface when using adaptive Gaussians, showing that the standard relation between the bias and the free energy does not hold. We illustrate on the case of alanine dipeptide the advantage of using adaptive Gaussians and the new free-energy estimator both for accuracy and speed of convergence [J. Chem. Theory Comput. 8, 2247 (2012)].

Metadynamics with adaptive Gaussians

245th National Meeting (2013)

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