Pseudopotentials from orbital-dependent exchange-correlation functionals

Norm-conserving pseudopotentials are generated on the basis of the optimized potential method (OPM), combining the exact exchange with two different correlation functionals, i.e., the orbital-dependent form of Colle and Salvetti (CS) [Theor. Chim. Acta 37, 329 (1975)] and the local density approximation (LDA). Application of both types of OPM pseudopotentials to a number of diatomic molecules leads to substantially different predictions for spectroscopic constants, thus indicating the importance of a suitable choice for the correlation functional to be used in the OPM context. Moreover, while the CS values are closet to the experimental data, our results nevertheless indicate that a really adequate correlation functional for use with the exact exchange is not yet available. In any case, both variants of the OPM-based pseudopotentials show an improved transferability compared with standard LDA pseudopotentials. [S1050-2947(98)03811-6].