The solvent region is defined on the grid used for the model electron
density
generation for the FFT, which is initialized to the bulk solvent level
at each
point. By default, the bulk solvent density is 1.0
e Å to simplify scaling (see below).
For each model atom, all grid points lying within
the sum of the half van der Waals radii of the model
atoms and an input solvent
radius are set to zero. After passing through all model atoms, the remaining
nonzero points define the solvent region. To avoid overcounting the solvent
points at the borders of the asymmetric units,
the entire unit cell is generated from this grid and the Fourier transform
computed in .