Real-space post-Hartree–Fock correlation models

Real-space models of nondynamical correlation between electrons of opposite spin and of parallel spin in multicenter (molecular) systems are discussed. These models are designed to be partnered with Hartree–Fock or exact Kohn–Sham exchange. Thus the numerous and well-known problems of local density-functional exchange-correlation approximations, especially in stretched odd-electron systems, are circumvented.