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In the framework of density functional theory a formalism to describe electronic transport in the steady state is proposed which uses the density on the junction and the {\em steady current} as basic variables. We prove that, in a finite…

Mesoscale and Nanoscale Physics · Physics 2016-01-12 G. Stefanucci , S. Kurth

We present an extension of the second-principles density functional theory (SPDFT) method to perform time-dependent simulations. Our approach, which calculates the evolution of the density matrix in real time and real space using the…

Materials Science · Physics 2025-07-21 Toraya Fernández-Ruiz , Jorge Íñiguez , Javier Junquera , Pablo García-Fernández

In this work we put forward an exact one-particle framework to study nano-scale Josephson junctions out of equilibrium and propose a propagation scheme to calculate the time-dependent current in response to an external applied bias. Using a…

Mesoscale and Nanoscale Physics · Physics 2015-05-14 Gianluca Stefanucci , Enrico Perfetto , Michele Cini

Evaluating the time-dependent dynamics of driven open quantum systems is relevant for a theoretical description of many systems, including molecular junctions, quantum dots, cavity-QED experiments, cold atoms experiments and more. Here, we…

Mesoscale and Nanoscale Physics · Physics 2017-08-23 Archak Purkayastha , Yonatan Dubi

The prominence of density functional theory (DFT) in the field of electronic structure computation stems from its ability to usefully balance accuracy and computational effort. At the base of this ability is a functional of the electron…

The effective action for the current and density is shown to satisfy an evolution equation, the functional generalization of Callan-Symanzik equation. The solution describes the dependence of the one-particle irreducible vertex functions on…

Condensed Matter · Physics 2009-11-07 Janos Polonyi

In the current density functional theory of linear and nonlinear time-dependent phenomena, the treatment of exchange and correlation beyond the level of the adiabatic local density approximation is shown to lead to the appearance of…

Condensed Matter · Physics 2009-10-30 G. Vignale , C. A. Ullrich , S. Conti

I show that the so-called causality paradox of time-dependent density functional theory arises from an incorrect formulation of the variational principle for the time evolution of the density. The correct formulation not only resolves the…

Materials Science · Physics 2009-11-13 G. Vignale

This paper gives an introduction to the Keldysh formalism, with emphasis on its usefulness in time-dependent density functional theory. In the first part we introduce the Keldysh contour and the one-particle Green function defined on this…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Robert van Leeuwen , Nils Erik Dahlen , Gianluca Stefanucci , Carl-Olof Almbladh , Ulf von Barth

Starting from a general classical model of many interacting particles we present a well defined step by step procedure to derive the continuum-mechanics equations of nonlinear elasticity theory with fluctuations which describe the…

Statistical Mechanics · Physics 2022-06-02 Rudolf Haussmann

Turbulent flows in the solar wind, large scale current sheets, multiple current sheets, and shock waves lead to the formation of environments in which a dense network of current sheets is established and sustains "turbulent reconnection".…

Solar and Stellar Astrophysics · Physics 2016-08-17 Loukas Vlahos , Theophilos Pisokas , Heinz Isliker , Vassilios Tsiolis , Anastasios Anastasiadis

Real-time time-dependent density functional theory (RT-TDDFT) can in principle access the whole absorption spectrum of a many-electron system exposed to a narrow pulse. However, this requires an accurate and efficient propagator for the…

Chemical Physics · Physics 2024-06-19 Linfeng Ye , Hao Wang , Yong Zhang , Wenjian Liu

Consider a system of particles evolving as independent and identically distributed (i.i.d.) random walks. Initial fluctuations in the particle density get translated over time with velocity $\vec{v}$, the common mean velocity of the random…

Probability · Mathematics 2010-09-15 Rohini Kumar

We consider a class of deterministic local collisional dynamics, showing how to approximate them by means of stochastic models and then studying the fluctuations of the current of energy. We show first that the variance of the…

Mathematical Physics · Physics 2015-05-19 Raphael Lefevere , Mauro Mariani , Lorenzo Zambotti

The advent of the Hohenberg-Kohn theorem in 1964, its extension to finite-T, Kohn-Sham theory, and relativistic extensions provide the well-established formalism of density-functional theory (DFT). This theory enables the calculation of all…

Quantum Physics · Physics 2013-07-18 M. W. C. Dharma-wardana

The Hohenberg-Kohn theorem of the density functional theory is extended by modifying the Levy constrained-search formulation. The new theorem allows us to choose arbitrary physical quantities as the basic variables which determine the…

Condensed Matter · Physics 2009-11-10 M. Higuchi , K. Higuchi

In the present work we propose a theory for obtaining successively better approximations to the linear response functions of time-dependent density or current-density functional theory. The new technique is based on the variational approach…

Statistical Mechanics · Physics 2007-05-23 Ulf von Barth , Nils Erik Dahlen , Robert van Leeuwen , Gianluca Stefanucci

The quantum theory of conductivity of semiconductor objects, to which the quantum wells, wires and dots concern, is constructed. Average values of current and charge densities, induced by a weak electromagnetic field, are calculated. It is…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 I. G. Lang , L. I. Korovin , J. A. de la Cruz Alcaz , S. T. Pavlov

Within Current Density Functional Theory, we have studied a quantum dot made of 210 electrons confined in a disk geometry. The ground state of this large dot exhibits some features as a function of the magnetic field (B) that can be…

Condensed Matter · Physics 2009-10-30 Marti Pi , Manuel Barranco , Agusti Emperador , Enrico Lipparini , Llorens Serra

Excitonic effects in the optical absorption spectra of solids can be described with time-dependent density-functional theory (TDDFT) in the linear-response regime, using a simple class of approximate, long-range corrected (LRC)…

Materials Science · Physics 2025-04-10 Jared R. Williams , Carsten A. Ullrich