Numerical computation of critical properties and atomic basins from 3D   grid electron densities
  InteGriTy is a software package that performs topological analysis following AIM approach on electron densities given on 3D grids. Use of tricubic interpolation is made to get the density, its gradient and hessian matrix at any required position. Critical points and integrated atomic properties have been derived from theoretical densities calculated for the compounds NaCl and TTF-2,5Cl2BQ, thus covering the different kinds of chemical bonds: ionic, covalent, hydrogen bonds and other intermolecular contacts. 
C. Katan, P. Rabiller, C. Lecomte, M. Guezo, V. Oison and M. Souhassou