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The widespread use of (generalized) Kohn-Sham density functional theory (KS-DFT) lies in the fact that hierarchical sets of approximations of the exchange-correlation (XC) energy functional can be designed, offering versatile choices to…

Materials Science · Physics 2023-01-31 Igor Ying Zhang , Xinguo Ren

Elucidating the impact of strong electronic interactions on the collective excitations of metallic systems has been of longstanding interest, mainly due to the inadequacy of the random phase approximation (RPA) in the strongly correlated…

Strongly Correlated Electrons · Physics 2024-09-25 Loïc Philoxene , Vu Hung Dao , Raymond Frésard

The practical Domain Adaptation (DA) tasks, e.g., Partial DA (PDA), open-set DA, universal DA, and test-time adaptation, have gained increasing attention in the machine learning community. In this paper, we propose a novel approach, dubbed…

Computer Vision and Pattern Recognition · Computer Science 2024-04-29 Xiang Gu , Xi Yu , Yan Yang , Jian Sun , Zongben Xu

The matrix equations of the random-phase approximation (RPA) are derived for the point-coupling Lagrangian of the relativistic mean-field (RMF) model. Fully consistent RMF plus (quasiparticle) RPA illustrative calculations of the isoscalar…

Nuclear Theory · Physics 2009-11-11 T. Niksic , D. Vretenar , P. Ring

We present a method to approximate post-Hartree-Fock correlation energies by using approximate natural orbitals obtained by the random phase approximation (RPA). We demonstrate the method by applying it to the helium atom, the hydrogen and…

Chemical Physics · Physics 2021-03-22 Benjamin Ramberger , Zoran Sukurma , Tobias Schäfer , Georg Kresse

Nucleon self-energies for 40Ca, 48Ca, 60Ca isotopes are generated with the microscopic Faddeev-random-phase approximation (FRPA). These self-energies are compared with potentials from the dispersive optical model (DOM) that were obtained…

Nuclear Theory · Physics 2015-05-28 S. J. Waldecker , C. Barbieri , W. H. Dickhoff

We consider an analytically solvable model of two interacting electrons that allows for the calculation of the exact exchange-correlation kernel of time-dependent density functional theory. This kernel, as well as the corresponding density…

Strongly Correlated Electrons · Physics 2017-05-04 Luis Cort , Daniel Karlsson , Giovanna Lani , Robert van Leeuwen

In this work we explore the performance of approximations to electron correlation in reduced density-matrix functional theory (RDMFT) and of approximations to the observables calculated within this theory. Our analysis focuses on the…

Strongly Correlated Electrons · Physics 2015-02-26 Stefano Di Sabatino , Jan A. Berger , Lucia Reining , Pina Romaniello

We derive a local approximation for the correlation energy in two-dimensional electronic systems. In the derivation we follow the scheme originally developed by Colle and Salvetti for three dimensions, and consider a Gaussian approximation…

Strongly Correlated Electrons · Physics 2008-11-21 S. Pittalis , E. Rasanen , M. Marques

We introduce the Korringa-Kohn-Rostocker non-local coherent potential approximation (KKR-NLCPA) for describing the electronic structure of disordered systems. The KKR-NLCPA systematically provides a hierarchy of improvements upon the widely…

Materials Science · Physics 2009-11-07 D. A. Rowlands , J. B. Staunton , B. L. Gyorffy

We recently introduced the dynamical cluster approximation(DCA), a new technique that includes short-ranged dynamical correlations in addition to the local dynamics of the dynamical mean field approximation while preserving causality. The…

Strongly Correlated Electrons · Physics 2009-10-31 M. H. Hettler , M. Mukherjee , M. Jarrell , H. R. Krishnamurthy

Random Phase Approximation (RPA) is the theory most commonly used to describe the excitations of many-body systems. In this article, the secular equations of the theory are obtained by using three different approaches: the equation of…

Nuclear Theory · Physics 2023-03-14 Giampaolo Co'

To investigate inelastic electron scattering, which is ubiquitous in various fields of study, we carry out ab initio study of the real-time dynamics of a one-dimensional electron wave packet scattered by a hydrogen atom using different…

Atomic Physics · Physics 2020-06-24 Yeonghun Lee , Xiaolong Yao , Massimo V. Fischetti , Kyeongjae Cho

A widely used approximation to the exchange-correlation functional in density functional theory is the local density approximation (LDA), typically derived from the properties of the homogeneous electron gas (HEG). We previously introduced…

Other Condensed Matter · Physics 2018-06-27 Mike Entwistle , Michele Casula , Rex Godby

We present a comparative study of particle-hole and particle-particle channels of random-phase approximation (RPA) for molecular dissociations of different bonding types. We introduced a \textit{direct} particle-particle RPA scheme, in…

Materials Science · Physics 2019-06-05 Muhammad N. Tahir , Xinguo Ren

The coherent potential approximation (CPA) is extended to describe satisfactorily the motion of particles in a random potential which is spatially correlated and smoothly varying. In contrast to existing cluster-CPA methods, the present…

Disordered Systems and Neural Networks · Physics 2009-10-20 Roland Zimmermann , Christoph Schindler

The accuracy of the constrained random phase approximation(cRPA) method is examined in multi-orbital Hubbard models containing all possible on-site density-density interactions. Using DMFT, we show that the effective model constructed using…

Strongly Correlated Electrons · Physics 2018-10-16 Qiang Han , B. Chakrabarti , K. Haule

We introduce a generalization (gLDA) of the traditional Local Density Approximation (LDA) within density functional theory. The gLDA uses both the one-electron Seitz radius $\rs$ and a two-electron hole curvature parameter $\eta$ at each…

Chemical Physics · Physics 2015-06-18 Pierre-François Loos , Caleb J. Ball , Peter M. W. Gill

We study the dynamics of a single Frenkel exciton in a disordered molecular chain. The coherent-potential approximation (CPA) is applied to the situation when the single-molecule excitation energies as well as the transition dipole moments,…

Disordered Systems and Neural Networks · Physics 2011-05-11 D. B. Balagurov , G. C. La Rocca , V. M. Agranovich

A novel treatment of non-adiabatic couplings is proposed. The derivation starts from the long-known, but not well-known, fact that the wave function of the complete system of elctrons and nuclei can be written, without approximation, as a…

Materials Science · Physics 2007-05-23 Nikitas I. Gidopoulos , E. K. U. Gross