| Abstract: | Two points about correlation potentials have been dealt with in this article. The first one is related to the shape of some of the most representative correlation potentials applied to the ground state of the He atom. It is shown here that both LDA and two-body density correlation potentials compare well with that obtained through the quantum chemistry definition of correlation energy. This is an interesting result because, in previous works, it had been shown that none of the correlation potentials compared well with the Kohn–Sham one. The gradient-corrected correlation potentials exhibit a very different behavior to that of both exact potentials (quantum chemistry and Kohn–Sham ones). The other question posed here refers to how a reference to the two-body density must modify DFT functionals for the correlation energy, when a multideterminant wave function is needed. This question has been addressed by analyzing the variation of correlation potentials as the bond length of the H2 molecule increases. The results show that an external reference to the two-body density qualitatively improves DFT correlation potentials and also that only those functionals explicitly depending on two-body density can give the quantitative correct trends. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 67: 143–156, 1998 |
