Localized electronic states in Mo near a <100> edge dislocation compared with perfect lattice, ch. 6

A new quantum mechanical method is developed for investigating the localized electronic states near dislocations in metals using the formalism of multiple scattering theory. The computer simulation procedure for calculating the atomic configuration of dislocations is combined with classical linear elasticity theory and with the self-consistent scattered wave model. A method is outlined for calculating the electronic states in Mo near a <100> [100] edge dislocation and those in the perfect lattice. The charge densities in each point of the cluster of nine Mo atoms are determined by superimposing atomic densities calculated by the Dirac-Slater formalism. For the purpose of comparison, similar results were obtained from the relativistic Hartree-Fock model. The orbital energies show only a slight difference between the results obtained using atomic configurations determined by two computational procedures (0.002% of the total energy). The highest occupied orbital energy in the dislocated lattice is -0.44l Ryd. while for the perfect lattice -0.513 Ryd. was found. This implies the presence of a small electronic field gradient around the dislocation line; a corresponding redistribution of the electronic energies is obtained. The width of the totally filled d-band near the dislocation is 0.16 Ryd. and for the perfect lattice it is 0.25 Ryd. From photo-emission and optical reflection measurements of Mo predict energy levels at -0.037 Ryd., -0.118 Ryd., -0.287 Ryd. below and 0.290 Ryd. above the Fermi level are obtained. The corresponding values calculated for the perfect system are: -0.041 Ryd., -0.128 Ryd., -0.238 Ryd. below and 0.209 Ryd. above it. The results are in good agreement with those obtained using the APW technique. Further possible extensions utilizing the 'scattered wave' method are briefly indicated