Variationally Enhanced Sampling
The Variationally Enhanced Sampling (VES) method  is born as an evolution of Metadynamics, and shares with it the idea of enhancing the sampling by biasing some collective variables which characterize the system under investigation.
It reduces the procedure of finding the free energy surface to the problem of minimizing the following convex functional:
 O. Valsson, and M. Parrinello, "Variational approach to enhanced sampling and free energy calculations." Physical review letters 113.9 (2014): 090601.
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