Antiferromagnetic Exchange Interactions from Hybrid Density Functional Theory

A hybrid theory which combines the full nonlocal “exact” exchange interaction with the local spin-density approximation of density-functional theory is shown to lead to marked improvement in the description of antiferromagnetically coupled systems. Semiquantitative agreement with experiment is found for the magnitude of the coupling constant in ${\mathrm{La}}_2{\mathrm{CuO}}_4$, ${\mathrm{KNiF}}_3$, and ${\mathrm{K}}_2{\mathrm{NiF}}_4$. The magnitude of the unpaired spin population on the metal site is in excellent agreement with experiment for ${\mathrm{La}}_2{\mathrm{CuO}}_4$.