Crystal structure and phase stability in Fe_(1-x)Co_x from AB initio theory

摘要

The crystal structure for many metals is well established, and early research discovered a pattern which was shown to depend on the chemical periodicity of these elements. Particularly for the non-magnetic metals in the 4d and 5d transition metal series a connection between the atomic number and the crystal structure was recognized~1. The crystal structure sequence involved more (fcc and hcp) or less (bcc) close-packed structures with high symmetry. The fact that the rare-earch elements show a regular behavior of the crystal structure as a function of atomic number led to the proposal~2 that the occupation of the d states was the important parameter for the crystal structure for these metals. This could then explain the more dramatic behavior of the d transition metals compared to the rare-earths since for the latter the occupation of the d states does not change much over series whereas for the transition metals the d band is successively being filled when proceeding through the series.