Fully relativistic calculations of the effect of pressure on the magnetismof EuCO2P2

Self-consistent moment-polarized four-component relativistic electronic str ucture calculations were performed for embedded clusters representing the l ayered compound EuCo2P2 of ThCr2Si2-type structure, with lattice parameters a and c corresponding to ambient pressure and to pressure equal to 3.5 GPa . The relativistic discrete variational method in density functional theory was employed. It was found that the Eu sublattice moments, which order ant iferromagnetically at ambient pressure, are supressed at high pressures; in versely, magnetism appears in the Co layer. However, only a small change wi th pressure in the charge of Eu, from + 2.0 to + 2.2, was derived from the calculations. (C) 2001 Elsevier Science B.V. All rights reserved.