Dipole fields and electric-field gradients in their dependence on the macroscopic and microscopic crystal parameters for orthorhombic and hexagonal lattices. II

Abstract

Lorentz factors ( L) at the lattice sites in simple orthorhombic lattices have been calculated by the method of Ewald and Born to a high degree of accuracy (error, either relative or absolute, 10 -11) and their dependence on the structure is discussed in terms of the difference between the actual Lorentz factor and the one belonging to the corresponding one- or two-dimensional structure. It turns out that L along the shortest axis of simple orthorhombic lattices can, even in not extreme cases of axis ratios, be described by a layer or chain picture, but for L corresponding to the middle axis a hybrid view is appropriate. The Lorentz coefficient is evaluated for simple rectangular lattices by applying the Ewald-Born method in two dimensions. Superposition considerations are used to treat the hexagonal and trigonal lattices and to correlate manganese nuclear quadrupole splittings with details of the crystal structure in K 2MgF 4:Mn.