Density-gradient expressions for the correlation-energy of many-electron systems

摘要

Based on gradient expansion approximations to an earlier proposed method [Chem. Phys. Lett. 175 (1990) 641; J. Mol. Struct. (Theochem) 287 (1993) 11] we presently report a new derivation of correlation functionals. Their application to atoms and molecules is discussed. A relation between the correlation energy and the expectation value of r~2 is derived.