and NRMSD ens is a measure of the convergence obtained with increasing N. This is plotted in Fig 5d , showing large initial fluctuations for N<6, followed by a smooth convergence behaviour afterwards. Limited improvement is observed for N>12, and a 10 % residual error remains up to N=20. Although further increase of N is expected to improve the convergence, considering about 10 to 20 conformers instead of 2000 represents a huge advantage in terms of computational cost at the expense of a more than acceptable error.