We apply ab initio quantum-chemical methods to calculate correlation effects on cohesive properties of GdN, thereby extending the recently proposed incremental method to rare-earth compounds. Our calculated values are in reasonable agreement with the experimental cohesive energy (86.0%) and the experimental lattice constant (102.0%). Furthermore, we calculate a bulk modulus of 140.3 GPa. Taking into account estimates for the effect of a better basis both at the one-particle level and at the many-particle level, we even reach 98.5% of the experimental cohesive energy and 101.3% of the experimental lattice constant. For this estimate, we obtain a bulk modulus of 163.8 GPa.

• Received 18 August 1997

DOI:https://doi.org/10.1103/PhysRevB.57.2127