  Biased sampling of collective variables is widely used to accelerate rare
events in molecular simulations and to explore free energy surfaces. However,
computational efficiency of these methods decreases with increasing number of
collective variables, which severely limits the predictive power of the
enhanced sampling approaches. Here we propose a method called Temperature
Accelerated Sliced Sampling (TASS) that combines temperature accelerated
molecular dynamics with umbrella sampling and metadynamics to sample the
collective variable space in an efficient manner. The presented method can
sample a large number of collective variables and is advantageous for
controlled exploration of broad and unbound free energy basins. TASS is also
shown to achieve quick free energy convergence and is practically usable with
ab initio molecular dynamics techniques.
