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We present a systematic study of vertex corrections in the homogeneous electron gas at metallic densities. The vertex diagrams are built using a recently proposed positive-definite diagrammatic expansion for the spectral function. The…

Strongly Correlated Electrons · Physics 2016-11-15 Y. Pavlyukh , A. -M. Uimonen , G. Stefanucci , R. van Leeuwen

For the Hirshfeld-I atom-in-molecule model, associated single-atom energies and interaction energies at the Hartree-Fock level are determined efficiently in one-electron Hilbert space. In contrast to most other approaches, the energy terms…

The increasing interest in the Mueller density-matrix-functional theory has led us to a systematic mathematical investigation of its properties. This functional is similar to the Hartree-Fock functional, but with a modified exchange term in…

Strongly Correlated Electrons · Physics 2009-09-29 Rupert L. Frank , Elliott H. Lieb , Robert Seiringer , Heinz Siedentop

Extended Lagrangian Born-Oppenheimer molecular dynamics [{\em Phys.\ Rev.\ Lett.\ } {\bf 2008}, {\em 100}, 123004] is presented for Hartree-Fock theory, where the extended electronic degrees of freedom are represented by a density matrix,…

Computational Physics · Physics 2020-05-29 Anders M. N. Niklasson

The exact reduced density-matrix functional is derived from the Luttinger-Ward functional of the single-particle Green's function. Thereby, a formal link is provided between diagrammatic many-body approaches using Green's functions on the…

Strongly Correlated Electrons · Physics 2013-12-11 Peter E. Blöchl , Thomas Pruschke , Michael Potthoff

We establish necessary and sufficient conditions for the N-representability of the universal one-electron reduced density matrix functional. Functionals satisfying these conditions are guaranteed to yield variational upper bounds on the…

Quantum Physics · Physics 2026-04-08 Jannis Erhard , Paul W. Ayers

Two of the most widely used electronic structure theory methods, namely Hartree-Fock and Kohn-Sham density functional theory, both requires the iterative solution of a set of Schr\"odinger-like equations. The speed of convergence of such…

Chemical Physics · Physics 2024-06-06 S. Hazra , U. Patil , S. Sanvito

A general formulation of the equilibrium state of a many-electron system in terms of a (mixed-state, ensemble) density matrix operator in the Fock space, based on the maximum entropy principle, is introduced. Various characteristic…

Chemical Physics · Physics 2013-10-28 Robert Balawender , Andrzej Holas

We put forward a general procedure to obtain an approximate free energy density functional for any hard-core lattice gas, regardless of the shape of the particles, the underlying lattice or the dimension of the system. The procedure is…

Statistical Mechanics · Physics 2007-05-23 Luis Lafuente , Jose A. Cuesta

Recently, Tao and Mo proposed an accurate meta-generalized gradient approximation for the exchange-correlation energy. The exchange part is derived from the density matrix expansion, while the correlation part is obtained by improving the…

Chemical Physics · Physics 2017-10-11 Yuxiang Mo , Guocai Tian , Jianmin Tao

The two-dimensional (2D) homogeneous electron gas (HEG) is a fundamental model in quantum many-body physics. It is important to theoretical and computational studies, where exchange-correlation energies computed in it serve as the…

Strongly Correlated Electrons · Physics 2025-01-17 Yiqi Yang , Yubo Yang , Kun Chen , Miguel A. Morales , Shiwei Zhang

We derive simplified Faddeev type equations for the three particle T-matrix which are valid in the Hubbard model where only electrons with opposite spins interact. Using the approximation of dynamical mean field theory these equations are…

Strongly Correlated Electrons · Physics 2009-02-05 M. Himmerich , M. Letz

The construction of meta generalized gradient approximations based on the density matrix expansion (DME) is considered as one of the most accurate technique to design semilocal exchange energy functionals in two-dimensional density…

Materials Science · Physics 2018-05-09 Abhilash Patra , Subrata Jana , Prasanjit Samal

Background: The study of additional terms in functionals is relevant to better describe nuclear structure phenomenology. Among these terms, the tensor one is known to impact nuclear structure properties, especially in neutron-rich nuclei.…

Nuclear Theory · Physics 2023-03-29 F. Mercier , J. -P. Ebran , E. Khan

Microscopic input to a universal nuclear energy density functional can be provided through the density matrix expansion (DME), which has recently been revived and improved. Several DME implementation strategies are tested for neutron drop…

Nuclear Theory · Physics 2013-05-29 S. K. Bogner , R. J. Furnstahl , H. Hergert , M. Kortelainen , P. Maris , M. Stoitsov , J. P. Vary

An extension of the fermionic particle--particle propagator is presented, that possesses similar algebraic properties to the single--particle Green's function. In particular, this extended two--particle Green's function satisfies Dyson's…

chem-ph · Physics 2009-10-28 Joachim Brand , Lorenz S. Cederbaum

Based on the Schrodinger equation, exact expressions for the non-relativistic particle energy in the local external field and the external field potential are derived as inhomogeneous density functionals. On this basis, it is shown that,…

Statistical Mechanics · Physics 2011-03-24 V. B. Bobrov , S. A. Trigger

A generalization of the Density Functional Theory is proposed. The theory developed leads to single-particle equations of motion with a quasi-local mean-field operator, which contains a quasi-particle position-dependent effective mass and a…

Nuclear Theory · Physics 2009-11-07 V. B. Soubbotin , V. I. Tselyaev , X. Vinas

The molecular density functional theory of fluids provides an exact theory for computing solvation free energies in implicit solvents. One of the reasons it has not received nearly as much attention as quantum density functional theory for…

Statistical Mechanics · Physics 2019-02-04 David M. Rogers

The dynamical, long-wavelength longitudinal and transverse exchange-correlation potentials for a homogeneous electron gas are evaluated in a microscopic model based on an approximate decoupling of the equation of motion for the…

Condensed Matter · Physics 2009-10-30 S. Conti , R. Nifosi' , M P Tosi