Very accurate electron structure factors measured by a significantly improved transmission electron diffraction technique for polycrystalline samples were used in a high-resolution quantitative study of the electrostatic potentials in LiF, NaF, and MgO crystals. The spatial electrostatic potential distribution was obtained using an analytical structural κ-model adapted for electron diffraction. A topological analysis of the electrostatic potential, defining the features of the electrostatic field and the Coulomb force field in a crystal was developed. In addition to the topological analysis of the electron density, this approach provides a more complete description of the atomic interactions. The application of this approach to the characterization of bonding in a crystal has been demonstrated. The suitability of electron diffraction for determination of the core-electron binding energy is discussed.

Precise X-ray and high-energy transmission electron diffraction methods were used for the study of electron density and electrostatic potential in MgO crystals. The structure amplitudes were determined and their accuracy estimated using ab initio Hartree-Fock structure amplitudes as criteria. The electrostatic potential distributions, reconstructed using Fourier series from both X-ray and electron diffraction data, are in satisfactory mutual agreement and are similar to the theory. They, however, suffer from restricted experimental resolution and, therefore, the reconstruction of the electrostatic potential via an analytical structural model is preferable. The x model of electron density was adjusted to X-ray experimental structure amplitudes and those calculated by the HartreeFock method. The electrostatic potential, deformation electron density and the Laplacian of the electron density were calculated with this model. The critical points in both experimental and theoretical model electron densities were found and compared with those for procrystals from spherical atoms and ions. A disagreement 11 concerning the type of critical point at (Z,Z,0) in the area of low, near-uniform electron density is observed. It is noted that topological analysis of the electron density in crystals can be related with a close-packing concept.