Adaptive biasing

These difficulties can be circumvented by using the adaptive biasing force (ABF) method of Darve, Pohorille, and coworkers [18, 28, 29], which is based on unconstrained molecular dynamics simulations. This is a very efficient approach which begins by establishing a simple formula to calculate d,4/d from regular molecular dynamics in which is not constrained. This derivative represents the mean force acting on . Therefore if we remove this force from the system we obtain... 

Call to ABF subroutine, which computes the derivative of the free energy using (4.33) and adds the adaptive biasing force. It takes as input the current acceleration al and returns the new acceleration with ABF added. /... 

Applies the adaptive biasing force, al is the new acceleration. This is an output variable. M is a diagonal matrix with atom masses. /... 

Darve, E., Rodrfguez-Gomez, D., Pohorille, A. Adaptive biasing force method for scalar and vector free energy calculations. J. Chem. Phys. 128(14) (2008). doi 10.1063/1.2829861... 

Dickson, B., Legoll, F, Lelievre, T, Stoltz, G., Fleurat-Lessard, R Free energy calculations An efficient adaptive biasing potential method. J. Phys. Chem. B 114(17), 5823-5830 (2010). doi 10.1021/jpl00926h... 

Lelievre, T, Rousset, M., Stoltz, G. Long-time convergence of an adaptive biasing force method. Nonlinearity 21(6) (2008). doi 10.1088/0951-7715/21/6/001... 

Component Monte Carlo An Adaptive Biasing Method for Open System Atomistic Simulations. 

In short, WTMetaD allows performing a simulation where, in the long time limit, the effective temperature of one or more selected CVs is kept at an arbitrarily high value T -I- AT. For AT oo, standard metadynamics is recovered (see Section Adaptive Biasing with Metadynamics ). For AT = 0, unbiased sampling is recovered. 

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