Search query: nonlocal density functional approximation for

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abstract: Using the weighted density approximation for the exchange correlation energy, the band structure and bulk structural properties of the prototypical semiconductors Si and Ge have been systematically studied. The weighted density approximation is based on an improved description of the exchange correlation hole that explicitly accounts for the inhomogeneous charge density found in real materials. We find that the approximation as proposed is inadequate for the case of semiconductors where charge inhomogeneity is intimately connected to a gap in the excitation spectrum with consequent qualitative changes in screening. We use a simple extension of the weighted density approximation which takes account of semiconductor screening. With this functional, we find substantial improvement in the calculated minimum gap over the results of the usual local density approximation as compared to experiment. However, the direct gaps are not significantly improved. Calculated structural properties are, moreover, found to be in excellent agreement with experiment. By way of contrast, the weighted density approximation implemented with metallic screening gives a smaller change in the band structure and more importantly, substantially poorer calculated structural properties. A discussion of the qualitative differences between the weighted density approximation and the usual local density approximation for covalently bonded semiconductors is presented.
author_names: Mark S Hybertsen

Steven G Louie
title: Nonlocal density functional approximation for exchange and correlation in semiconductors
year: 1984

abstract: In this paper we formulate a nonlocal density functional theory of inhomogeneous water. We model a water molecule as a couple of oppositely charged sites. The negatively charged sites interact with each other through the Lennard Jones potential (steric and dispersion interactions) square well potential (short range specific interactions due to electron charge transfer) and Coulomb potential, whereas the positively charged sites interact with all types of sites by applying the Coulomb potential only. Taking into account the nonlocal packing effects via the fundamental measure theory (FMT) dispersion and specific interactions in the mean field approximation, and electrostatic interactions at the many body level through the random phase approximation, we describe the liquid vapour interface. We demonstrate that our model without explicit account of the association of water molecules due to hydrogen bonding and with explicit account of the many body electrostatic interactions at the many body level is able to describe the liquid vapour coexistence curve and the surface tension at the ambient pressures and temperatures. We obtain very good agreement with available in the literature MD simulation results for density profile of liquid vapour interface at ambient state parameters. The formulated theory can be used as a theoretical background for describing of the capillary phenomena, occurring in micro and mesoporous materials.
author_names: Yu A Budkov

Andrei L Kolesnikov
title: Nonlocal density functional theory of water taking into account many body dipole correlations: Binodal and surface tension of 'liquid vapour' interface.
venue: Journal of physics. Condensed matter an Institute of Physics journal
year: 2020

author_names: Yuan Gao

Wenguang Zhu

Xinguo Ren
title: Long range behavior of a nonlocal correlation energy density functional based on the random phase approximation
year: 2020

abstract: Despite the large number of nonlocal kinetic energy density functionals (KEDFs) available for large scale calculation of extended systems, these KEDFs based on the Lindhard response function, in many cases, are not suitable for the isolated systems, where deviate from the uniform electron gas scenario. In this manuscript, we proposed a generalized scheme to construct nonlocal KEDFs via the local density approximated kernel. This scheme can significantly improve the accuracy and generality of orbital free density functional theory (OFDFT) to handle the isolated systems. We have implemented it into our developed ATLAS package under Dirichlet boundary condition and demonstrated the superior computational performances by several prototypical systems encompassing Mg, Si and GaAs clusters. The results show that the KEDFs constructed by our scheme can achieve high accuracy and numerical stability for simulations of isolated systems, applicable to design clusters and quantum dots containing a large number of atoms.
author_names: Qiang Xu

Jian Lv

Yanchao Wang

Yanming Ma
title: Construction of Nonlocal Kinetic Energy Density Functional via Local Density Approximation Kernel for Isolated Systems
year: 2019

abstract: We construct a free energy density functional approximation for the primitive model of the electrical double layer. The hard sphere term of the free energy functional is based on a nonlocal generic model functional proposed by Percus. This latter model functional, which is a generalization of the exact solution for the nonuniform hard rod model, requires as input the free energy of a homogeneous hard sphere mixture. We choose the extension of the Carnahan Starling equation of state to mixtures. The electrostatic part of the nonuniform fluid ion ion correlations present in the interface is approximated by that of a homogeneous bulk electrolyte. Using the mean spherical approximation for a neutral electrolyte, we apply the theory to symmetrical 1:1 and 2:2 salts in the restricted primitive model. We present comparisons of density profiles and diffuse layer potentials with Gouy Chapman theory and Monte Carlo data. We also compare our results with data from other recent theories of the double layer. For highl.
author_names: Luis Mier-Y-Teran

Soong Hyuck Suh

Henry S White

H Ted Davis
title: A nonlocal free energy density functional approximation for the electrical double layer
year: 1990

abstract: Abstract We use three gradient level and two nonlocal density functional approximations to study the thermodynamic properties of Cu Au compounds. It is found that a well designed gradient level approximation (quasi non uniform approximation, QNA) reproduces the experimental equilibrium volumes and the formation energies of L12 and L10 phases. On the other hand, QNA predicts a non existent b2 phase, which can be remedied only when employing the nonlocal hybrid level Heyd Scuseria Ernzerhof (HSE06) or Perdew Burke Ernzerhof (PBE0) approximations. Gradient level approximations lead to similar electronic structures for the Cu Au compounds whereas hybrids shift the d band towards negative energies and account for the complex d d hybridization more accurately.
author_names: Liyun Tian

Kalevi Kokko

Levente Vitos
title: Gradient level and nonlocal density functional descriptions of Cu Au intermetallic compounds
year: 2018

abstract: By invoking a divide and conquer strategy, subsystem DFT dramatically reduces the computational cost of large scale, ab initio electronic structure simulations of molecules and materials. The central ingredient setting subsystem DFT apart from Kohn Sham DFT is the non additive kinetic energy functional (NAKE) Currently employed NAKEs are at most semilocal (i.e. they only depend on the electron density and its gradient) and as a result of this approximation, so far large scale simulations only included systems composed of weakly interacting subsystems. In this work, we advance the state of the art by introducing fully nonlocal NAKEs in subsystem DFT simulations for the first time. A benchmark analysis based on the S22 5 test set shows that nonlocal NAKEs considerably improve the computed interaction energies and electron densities compared to commonly employed GGA NAKEs, especially when increasing inter subsystem electron density overlap is considered. Most importantly, we resolve the long standing problem of too attractive interaction energy curves typically resulting from the use of GGA NAKEs.
author_names: Wenhui Mi

Michele Pavanello
title: Nonlocal Subsystem Density Functional Theory.
venue: The journal of physical chemistry letters
year: 2019

abstract: Despite a large number of nonlocal kinetic energy density functionals (KEDFs) available for large scale calculations, most of those nonlocal KEDFs designed for the extended systems cannot be directly applied to isolated systems. In this manuscript, we proposed a generalized scheme to construct nonlocal KEDFs via the local density approximation kernels and construct a family of KEDFs for simulations of isolated systems within orbital free density functional theory. The performance of KEDFs has been demonstrated by several clusters encompassing Mg, Si and GaAs. The results show that our constructed KEDFs can achieve high numerical accuracy and stability for random clusters, therefore, making orbital free density functional theory accessible for practical simulations of isolated systems.
author_names: Qiang Xu

Jian Lv

Yanchao Wang

Yanming Ma
title: Nonlocal kinetic energy density functionals for isolated systems obtained via local density approximation kernels
year: 2020

abstract: A 10 parameter, range separated hybrid (RSH) generalized gradient approximation (GGA) density functional with nonlocal correlation (VV10) is presented. Instead of truncating the B97 type power series inhomogeneity correction factors (ICF) for the exchange, same spin correlation, and opposite spin correlation functionals uniformly, all 16,383 combinations of the linear parameters up to fourth order (m 4) are considered. These functionals are individually fit to a training set and the resulting parameters are validated on a primary test set in order to identify the 3 optimal ICF expansions. Through this procedure, it is discovered that the functional that performs best on the training and primary test sets has 7 linear parameters, with 3 additional nonlinear parameters from range separation and nonlocal correlation. The resulting density functional, oB97X V, is further assessed on a secondary test set, the parallel displaced coronene dimer, as well as several geometry datasets. Furthermore, the basis set dependence and integration grid sensitivity of oB97X V are analyzed and documented in order to facilitate the use of the functional.
author_names: Narbe Mardirossian

Martin Head-Gordon
title: oB97X V: a 10 parameter, range separated hybrid, generalized gradient approximation density functional with nonlocal correlation, designed by a survival of the fittest strategy.
venue: Physical chemistry chemical physics PCCP
year: 2014

abstract: Orbital Free Density Functional Theory (OF DFT) promises to describe the electronic structure of very large quantum systems, being its computational cost linear with the system size. However, the OF DFT accuracy strongly depends on the approximation made for the kinetic energy (KE) functional. To date, the most accurate KE functionals are non local functionals based on the linear response kernel of the homogeneous electron gas, i.e. the jellium model. Here, we use the linear response kernel of the jellium with gap model, to construct a simple non local KE functional (named KGAP) which depends on the band gap energy. In the limit of vanishing energy gap (i.e. in the case of metals) the KGAP is equivalent to the Smargiassi Madden (SM) functional, which is accurate for metals. For a series of semiconductors (with different energy gaps) the KGAP performs much better than SM, and results are close to the state of the art functionals with complicated density dependent kernels.
author_names: Lucian A Constantin

Eduardo Fabiano

Fabio Della Sala
title: Nonlocal kinetic energy functional from the jellium with gap model: Applications to orbital free density functional theory
year: 2018