  Metadynamics is an enhanced sampling method of great popularity, based on the
on-the-fly construction of a bias potential that is function of a selected
number of collective variables. We propose here a change in perspective that
shifts the focus from the bias to the probability distribution reconstruction,
while keeping some of the key characteristics of metadynamics, such as the
flexible on-the-fly adjustments to the free energy estimate. The result is an
enhanced sampling method that presents a drastic improvement in convergence
speed, especially when dealing with suboptimal and/or multidimensional sets of
collective variables. The method is especially robust and easy to use, in fact
it requires only few simple parameters to be set, and it has a straightforward
reweighting scheme to recover the statistics of the unbiased ensemble.
Furthermore it gives more control on the desired exploration of the phase
space, since the deposited bias is not allowed to grow indefinitely and it does
not push the simulation to uninteresting high free energy regions. We
demonstrate the performance of the method in a number of representative
examples.
