where A is the free energy profile as a function of the colvar ξ and F is the force exerted by the system onto the colvar. In principle, ξ is a continuous variable and equation 1 applies for every value ξ 0 . In practice, the colvar is divided into small bins of width ∆ξ and samples are aquired for each bin during the simulation to compute the mean force in the interval (ξ 0 , ξ 0 + ∆ξ). Then, the mean value of those samples for each bin is used to compute the gradient and, through integration, the PMF. The review by review by Comer et al. provides a more detailed description of the ABF method, together with recommendations and good practices.