Publication

Multicenter density functionals: revised expression of the standard approximations of exchange-correlation functional

Ursula Röthlisberger, Ivano Tavernelli, I-Chun Lin
2009
Journal Articles

Abstract

We propose to express corrections to the standard approximations of the exchange-correlation functionals in the form of multiatom-centered functionals that can be related to the atoms-in-molecules theory of Bader and a multicenter density expansion. Unlike conventional functionals, the variables of these multicenter functionals are the positions and identities of the nuclei, which can unambiguously be determined from the topology of the electronic density. The proposed multicenter correction is used to provide a theoretical basis for the dispersion-corrected atom-centered potential (DCACP) approach used to improve van der Waals interactions in conventional density functional theory. Convergence to the correct long-range asymptotic behavior of the multicenter expansion for DCACPs is demonstrated in the test case of the H-2 van der Waals dimer.

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https://infoscience.epfl.ch/entities/publication/62583917-bacb-4e06-9dde-c05171f4e466

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Ursula Röthlisberger, Ivano Tavernelli, I-Chun Lin
2009
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/62583917-bacb-4e06-9dde-c05171f4e466

About this result

Related concepts (19)

Density functional theory

Density-functional theory (DFT) is a computational quantum mechanical modelling method used in physics, chemistry and materials science to investigate the electronic structure (or nuclear structure) (principally the ground state) of many-body systems, in particular atoms, molecules, and the condensed phases. Using this theory, the properties of a many-electron system can be determined by using functionals, i.e. functions of another function. In the case of DFT, these are functionals of the spatially dependent electron density.

Local-density approximation

Local-density approximations (LDA) are a class of approximations to the exchange–correlation (XC) energy functional in density functional theory (DFT) that depend solely upon the value of the electronic density at each point in space (and not, for example, derivatives of the density or the Kohn–Sham orbitals). Many approaches can yield local approximations to the XC energy. However, overwhelmingly successful local approximations are those that have been derived from the homogeneous electron gas (HEG) model.

Electron density

Electron density or electronic density is the measure of the probability of an electron being present at an infinitesimal element of space surrounding any given point. It is a scalar quantity depending upon three spatial variables and is typically denoted as either or . The density is determined, through definition, by the normalised -electron wavefunction which itself depends upon variables ( spatial and spin coordinates). Conversely, the density determines the wave function modulo up to a phase factor, providing the formal foundation of density functional theory.

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