The effect of hydrogenation on the crystal structure and magnetic state inPd3Mn

The effect of hydrogenation on the crystal structure and magnetic state of Pd3Mn has been calculated using a full-potential linear augmented plane wav e method in the local spin density approximation. When hydrogenated the sys tem is observed to transform from the tetragonal Al3Zr structure to the cub ic Cu3Au structure. When hydrogen is removed the system remains in a meta-s table cubic phase for an extended period of time. The structural transforma tions are associated with a change in the magnetic state. Our theoretical r esults of magnetic as well as crystal structure stability are in agreement with experiments, especially the destabilization of the tetragonal structur e for increased hydrogen concentration and complex magnetic structure of th e cubic phases. The latter is analyzed in terms of Fermi surface nesting. ( C) 2001 Elsevier Science B.V. All rights reserved.