Broken-symmetry-adapted Green function theory of condensed matter systems: Towards a vector spin-density-functional theory

Broken symmetry in density-functional theory: Analysis and cure

We present a detailed analysis of the broken-symmetry mean-field solutions using a four-electron rectangular quantum dot as a model system. Comparisons of the density-functional theory predictions with the exact ones show that the symmetry-breaking results from the single-configuration wave function used in the mean-field approach. As a general cure we present a scheme that systematically incor...

INTERNATIONAL SCHOOL FOR ADVANCED STUDIES CONDENSED MATTER THEORY SECTOR Non-local correlation in Density Functional Theory

A Density Functional Theory Study of Structure of Phosphonic Acid

The molecular structure of the stable conformation of phosphonic acid in gas phase has beencomputed by employing complete geometry optimization in Density Functional Theory(DFT) methods. The methods used for calculations are B3LYP, BP86 and B3PW91 that havebeen studied in two series of basis sets: D95** and 6-31+G(d,p) for hydrogen and oxygenatoms; LANL2DZ for phosphorus. Bond lengths and angle...

A Density Functional Theory Study of Boron Nitride Nano-Ribbons

The electronic and structural properties of pristine and carbon doped (C-doped) boron nitride nano-ribbons(BNNRs) have been studied employing density functional theory (DFT) calculations. Total energies, gapenergies, dipole moments, and quadrupole coupling constants (qcc) have been calculated in the optimizedstructures of the investigated BNNRs. The results indicated that the stability and gap ...

Escaping the symmetry dilemma through a pair-density interpretation of spin-density functional theory.

In the standard interpretation of spin-density functional theory, a self-consistent Kohn-Sham calculation within the local spin density (LSD) or generalized gradient approximation (GGA) leads to a prediction of the total energy E, total electron density n(r) =n~(r)+n ~(r), and spin magnetization density m(r)=n~(r) —n~(r). This interpretation encounters a serious symmetry dilemma" for H2, Cr2, a...