The CombineGrids tab is used to incorporate the receptor's mobility in docking calculations based on the work of Österberg et al. (2002). Briefly, this method combines all the grid maps from the different receptor conformations and the same probe to obtain a single grid-map file. In this file, the energy of each point is obtained from a weighted average of the energies of the same point in all the original conformational-dependent grid maps (where the corresponding weight is calculated using either a clamped grid or a Boltzmann assumption based on the interaction energy). The Fortran program under this tab is combine_grids and the resulting grid maps can be readily used by the MakeDocks tab.