Publication

A first principles study of small Cu-n clusters based on local-density and generalized-gradient approximations to density functional theory

Alfredo Pasquarello
1998
Journal Articles

Abstract

Neutral and anionic Cu-n clusters (Cu-2, Cu-3, Cu-6 and Cu-7(-)) are studied within density functional theory via (a) the local-density approximation (LDA) and (b) the generalized-gradient approximation (GGA) of Perdew and Wang (GGA-PW) for exchange and correlation. GGA reduces by similar to 20% the binding energies, while the bond lengths are increased by similar to 3-4%. The different levels of GGA approximation, involving optimization of the electronic density and/or of the geometry, are shown in detail. In the case of Cu-6 the GGA configurational ground state is a planar structure of D-3h symmetry. This result differs from the one obtained by LDA, where the three different isomers (one two-dimensional and two three-dimensional) were found to lie within 0.04 eV.

Official source

https://infoscience.epfl.ch/entities/publication/a0d8434c-5fde-4289-be8f-b5d80d15aca7

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Alfredo Pasquarello
1998
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/a0d8434c-5fde-4289-be8f-b5d80d15aca7

About this result

Related concepts (32)

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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A first principles study of small Cu-n clusters based on local-density and generalized-gradient approximations to density functional theory

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