The Crystal Arrangement
It is possible to predict the geometry of a molecule. Can it also be predicted for a crystal? The large number of parameters (the coordinates of nuclei) prevents an ab initio investigation of the positions of atoms in a crystal. Naturally, the problem is simplified if one assigns a general pattern to the structure. The geometry depends on only one parameter. The minimization of the energy with respect to this parameter gives the geometry of the lattice. Such calculations have been performed for alkali-halides 41–42,diamond 63, and metals 29-26. The quality of the values obtained depends heavily on that of the wave function. In contrast, the charges seem less sensitive to this factor.
KeywordsCoordination Number Interatomic Distance Cohesive Energy Molecular Crystal Hybrid Orbital
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