Electronic structure and energetics of RCo5H4 and RCo5 (R=La,Pr)

Calculations of the spin-dependent electronic structure and enthalpies of formation, DeltaH, of the ternary hydrides LaCo5H4, PrCo5H4, and their parent intermetallics are reported. All four compounds are found to be metallic and ferromagnetic. We obtain DeltaH(LaCo5H4)=-45.6 kJ/mole H-2, DeltaH(PrCo5H4)=-39.8 kJ/mole H-2, and DeltaH(LaCo5)=-12.6 kJ/LaCo5, values which compare very favorably with experiment. With the assumption of the free-ion 4f moment for Pr, the calculated magnetic moments agree well with available measurements. (C) 2003 American Institute of Physics.