You are not logged in to this journal. Log in
| Subscription Information
Phys. Rev. A 73, 012511 (2006) [13 pages]Variational energy functionals of the Green function and of the density tested on molecules
Received 7 March 2005; published 31 January 2006
We have calculated total energies of atoms and diatomic molecules from the Luttinger-Ward functional, using self-energy approximations to second order as well as the GW approximation. In order to assess the variational quality of this functional, we have also solved the Dyson equation self-consistently. The Luttinger-Ward functional is compared to the variational functional due to Klein, and we demonstrate that the variational property of the latter functional is inferior to that of the Luttinger-Ward functional. We also show how to obtain variational density functionals from the functionals of the Green function. These orbital functional schemes are important for systems where density-functional theory using local functionals of the density necessarily fails. We derive an optimized effective potential (OEP) scheme that is based on the Luttinger-Ward functional and, unlike the conventional OEP schemes, produces energies in good agreement with the values obtained from the self-consistent Green function. Our calculations show that, when applied to molecules, the Luttinger-Ward functional is more sensitive to the quality of the input Green function than when applied to atoms, but the energies are remarkably close to the self-consistent values when the Hartree-Fock Green function is used as input. This Luttinger-Ward functional is therefore a simple and efficient method for studying the merits of various self-energy approximations while avoiding the computationally demanding task of solving the Dyson equation self-consistently. ©2006 The American Physical Society
REFERENCES (54)
For access to fully linked references, you need to log in.
For access to fully linked references, you need to Log in.
CITING ARTICLESFor access to citing articles, you need to log in.
For access to citing articles, you need to Log in.
|
Article Tools
|
|||||||||