Density matrix functional theory of weak intermolecular interactions

摘要

The known asymptotic behavior of thetotal energy of two weakly interacting systems imposes stringent conditions on the exchange-correlation energy as a functional of the one-electron reduced density matrix. Although the first-order conditions that involve Coulomb-type two-electron integrals are realtively trivial to satisfy, the exact functional should also conform to two second-order expressions, and consequently to certain sum rules. The primitive natural spin-ordital functionals satisfy the first-order conditions but, lacking terms quadratic in two-electron integrals, are found to be incapable of recovering the dispersion component of the interactin energy. Violating the sum rules, the recently proposed Yasuda funcitonal yields nonvanishing dispersion energy with spurious asymptotic terms that scale like inverse fourth and fifth powers of the intersystem distance.