COMPUTATION OF THE COHESIVE ENERGY, THE LATTICE PARAMETER, AND THE COMPRESSIBILITY OF IONIC CRYSTALS BY USING RADIALLY DEFORMED ATOMIC ORBITALS. II. NUMERICAL APPLICATIONS TO LIF,
UPPSALA UNIV (SWEDEN) QUANTUM CHEMISTRY GROUP
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The cohesive energy, the lattice parameter, and the compressibility of the static LiF crystal were determined in the Heitler-London scheme by means of three different quantum mechanical approximations. HartreeFock SCF-wave functions with exchange for Li - and F- -ions were used for the computations. The values for the cohesive energy, the lattice parameter, and the compressibility obtained from different approximations agree well with corresponding experimental data. However, remarkable improvements are gained when using the deformation model of the ions. The virial theorem, a necessary condition for an exact wave function, is satisfied in the third approximation. The values of the scaling parameters indicate that in the crystal F- -ions are contracted and Li -ions slightly extended as compared to the free ion states. The result is supported by the experimental measurements made on alkali halide crystals.
- Atomic and Molecular Physics and Spectroscopy
- Quantum Theory and Relativity
- Solid State Physics