scholarly journals Description of pairing correlation in many-body finite systems with density functional theory

2011 ◽  
Vol 83 (2) ◽  
Author(s):  
Guillaume Hupin ◽  
Denis Lacroix
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Pairing Correlation ◽  
Many Body ◽  
Functional Theory ◽  
Finite Systems

On the Nature of Halide-Water Interactions: Insights from Many-Body Representations and Density Functional Theory

2019 ◽  
Author(s):  
Brandon B. Bizzarro ◽  
Colin K. Egan ◽  
Francesco Paesani
Keyword(s):  
Density Functional Theory ◽  
Charge Transfer ◽  
Molecular Orbital ◽  
Density Functional ◽  
Decomposition Analysis ◽  
Orbital Energy ◽  
Energy Decomposition Analysis ◽  
Interaction Energies ◽  
Many Body ◽  
Functional Theory

<div> <div> <div> <p>Interaction energies of halide-water dimers, X<sup>-</sup>(H<sub>2</sub>O), and trimers, X<sup>-</sup>(H<sub>2</sub>O)<sub>2</sub>, with X = F, Cl, Br, and I, are investigated using various many-body models and exchange-correlation functionals selected across the hierarchy of density functional theory (DFT) approximations. Analysis of the results obtained with the many-body models demonstrates the need to capture important short-range interactions in the regime of large inter-molecular orbital overlap, such as charge transfer and charge penetration. Failure to reproduce these effects can lead to large deviations relative to reference data calculated at the coupled cluster level of theory. Decompositions of interaction energies carried out with the absolutely localized molecular orbital energy decomposition analysis (ALMO-EDA) method demonstrate that permanent and inductive electrostatic energies are accurately reproduced by all classes of XC functionals (from generalized gradient corrected (GGA) to hybrid and range-separated functionals), while significant variance is found for charge transfer energies predicted by different XC functionals. Since GGA and hybrid XC functionals predict the most and least attractive charge transfer energies, respectively, the large variance is likely due to the delocalization error. In this scenario, the hybrid XC functionals are then expected to provide the most accurate charge transfer energies. The sum of Pauli repulsion and dispersion energies are the most varied among the XC functionals, but it is found that a correspondence between the interaction energy and the ALMO EDA total frozen energy may be used to determine accurate estimates for these contributions. </p> </div> </div> </div>

EXCHANGE–CORRELATION KERNEL IN TIME-DEPENDENT DENSITY FUNCTIONAL THEORY DERIVED FROM MANY-BODY THEORY

2004 ◽  
Vol 18 (07) ◽  
pp. 1055-1067 ◽  
Author(s):  
K. KARLSSON ◽  
F. ARYASETIAWAN
Keyword(s):  
Density Functional Theory ◽  
Optical Absorption ◽  
Density Functional ◽  
Time Dependent ◽  
Many Body ◽  
Functional Theory ◽  
Correlation Kernel ◽  
Exchange Correlation ◽  
Many Body Theory ◽  
Dependent Density

We derive a simplified Bethe–Salpeter equation for calculating optical absorption based on the assumption of a local electron–hole interaction. The original four-point equation for the kernel is reduced to a two-point one. A connection to the exchange–correlation kernel in time-dependent density functional theory can be established. The resulting fxc is found to be -W/2 where W contains only the short-range (local) part of the Coulomb screened interaction. This simple approximation was successfully applied to optical absorption spectra of some excitonic crystals, reproducing not only the continuum excitons but also the bound ones.

scholarly journals Discontinuous Behavior of the Pauli Potential in Density Functional Theory as a Function of the Electron Number

2019 ◽  
Author(s):  
Eli Kraisler ◽  
Axel Schild
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Electron Systems ◽  
Electron Number ◽  
Functional Theory ◽  
Fractional Number ◽  
Finite Systems ◽  
Pauli Potential ◽  
Spin Polarized ◽  
Orbital Free

<div>The Pauli potential is an essential quantity in orbital-free density-functional theory (DFT) and in the exact electron factorization (EEF) method for many-electron systems. Knowledge of the Pauli potential allows the description of a system relying on the density alone, without the need to calculate the orbitals.</div><div>In this work we explore the behavior of the exact Pauli potential in finite systems as a function of the number of electrons, employing the ensemble approach in DFT. Assuming the system is in contact with an electron reservoir, we allow the number of electrons to vary continuously and to obtain fractional as well as integer values. We derive an expression for the Pauli potential for a spin-polarized system with a fractional number of electrons and find that when the electron number surpasses an integer, the Pauli potential jumps by a spatially uniform constant, similarly to the Kohn-Sham potential. The magnitude of the jump equals the Kohn-Sham gap. We illustrate our analytical findings by calculating the exact and approximate Pauli potentials for Li and Na atoms with fractional numbers of electrons.</div>

scholarly journals Including dispersion in density functional theory for adsorption on flat oxide surfaces, in metal–organic frameworks and in acidic zeolites

2020 ◽  
Vol 22 (14) ◽  
pp. 7577-7585 ◽  
Author(s):  
Florian R. Rehak ◽  
GiovanniMaria Piccini ◽  
Maristella Alessio ◽  
Joachim Sauer
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Van Der Waals ◽  
Metal Organic Frameworks ◽  
Many Body ◽  
Functional Theory ◽  
Metal Organic ◽  
The Many ◽  
Acidic Zeolites ◽  
Better Than

Contrary to common believe, for eight adsorption cases, neither D3 or TS are an improvement compared to D2 nor van der Waals functionals or dDsC. Only the many body approaches are slightly better than D2(Ne) which uses Ne parameters for Mg2+ ions.

COVARIANT DENSITY FUNCTIONAL THEORY FOR COLLECTIVE EXCITATIONS IN NUCLEI FAR FROM STABILITY

2006 ◽  
Vol 15 (02) ◽  
pp. 520-528 ◽  
Author(s):  
P. RING
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Random Phase ◽  
Effective Field ◽  
Many Body ◽  
Functional Theory ◽  
Quasiparticle Random Phase Approximation ◽  
System Use ◽  
Vibrational Excitations ◽  
Covariant Density

Modern methods for the description of the nuclear many-body system use the concepts of density functional theory (DFT) and of effective field theory (EFT). Relativistic Hartree Bogoliubov (RHB) theory is a covariant version of this method, which takes into account Lorentz symmetry and pairing correlations in a fully self-consistent way. This theory has been used in the past for a very successful phenomenological description of ground state properties of nuclei all over the periodic table. Recently is also has been extended for the investigation of excited states. We discuss the calculation of rotational bands within cranked RHB-theory and recent investigations of vibrational excitations within the framework of relativistic Quasiparticle Random Phase Approximation (QRPA).

scholarly journals Density Functional Theory Simulations of Semiconductors for Photovoltaic Applications: Hybrid Organic-Inorganic Perovskites and III/V Heterostructures

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Jacky Even ◽  
Laurent Pedesseau ◽  
Eric Tea ◽  
Samy Almosni ◽  
Alain Rolland ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Many Body ◽  
Electronic Band ◽  
Functional Theory ◽  
Photovoltaic Materials ◽  
Density Functional Perturbation Theory ◽  
Photovoltaic Applications ◽  
Photovoltaic Technologies ◽  
Structural And Optoelectronic Properties

Potentialities of density functional theory (DFT) based methodologies are explored for photovoltaic materials through the modeling of the structural and optoelectronic properties of semiconductor hybrid organic-inorganic perovskites and GaAs/GaP heterostructures. They show how the properties of these bulk materials, as well as atomistic relaxations, interfaces, and electronic band-lineups in small heterostructures, can be thoroughly investigated. Some limitations of available standard DFT codes are discussed. Recent improvements able to treat many-body effects or based on density-functional perturbation theory are also reviewed in the context of issues relevant to photovoltaic technologies.

Sign in / Sign up

Export Citation Format

Share Document