We used ACEMD [1] and the PLUMED [2] plugin to compute the phi-psi free energy landscape of the alanine dipeptide via well-tempered metadynamics. Observe how (especially at the beginning) the free energy basins are filled in turns.

Methods: the dipeptide was modelled in vacuo with the CHARMM forcefield. The total length of the run was 10 ns, simulated with a timestep of 1 fs. A total of 100,000 gaussians were deposited at a rate of one every 100 fs. The 1000 animation frames were taken at 10 ps intervals. Between each frame and the next, 100 new gaussians are deposited.

References:
[1] multiscalelab.org/acemd
[2] merlino.mi.infn.it/~plumed/PLUMED/Home.html