Binding energy curves from nonempirical density functionals II. van der Waals bonds in rare-gas and alkaline-earth diatomics.
Binding energy curves have been calculated for the ground-state rare-gas diatomics Ne(2) and Ar(2) and for the alkaline-earth diatomic Be(2) using the nonempirical density functionals from the first three rungs of a ladder of approximations: the local spin density (LSD) approximation, the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA), and the Tao-Perdew-Staroverov-Scuseria (TPSS) meta-GGA. Binding energy curves in reasonable agreement with those constructed from experiment are found from PBE and TPSS, which incorporate inhomogeneity corrections that satisfy the Lieb-Oxford bound and so describe the short-range part of the van der Waals interaction. At large internuclear separation, these functionals produce an exponentially decaying attraction in place of the correct long-range -C(6)/R(6). Basis-set and exchange-only effects are also discussed.
Ruzsinszky
Adrienn
A
Department of Physics and Quantum Theory Group, Tulane University, New Orleans, Louisiana 70118, USA..
Perdew
John P
JP
Csonka
Gábor I
GI