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We discuss two problems which are particularly challenging for approximations in time-dependent density functional theory (TDDFT) to capture: momentum-distributions in ionization processes, and memory-dependence in real-time dynamics. We…

Materials Science · Physics 2010-03-22 Arun K. Rajam , Paul Hessler , Christian Gaun , Neepa T. Maitra

Density functional theory (DFT) is a powerful theoretical tool widely used in such diverse fields as computational condensed matter physics, atomic physics, and quantum chemistry. DFT establishes that a system of $N$ interacting electrons…

Plasma Physics · Physics 2020-04-29 Giovanni Manfredi

We formulate a time-dependent density functional theory (TDDFT) in terms of the density matrix to study ultrafast phenomena in semiconductor structures. A system of equations for the density matrix components, which is equivalent to the…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 V. Turkowski , C. A. Ullrich

In this work we study the role of bound electrons in quantum transport. The partition-free approach by Cini is combined with time-dependent density functional theory (TDDFT) to calculate total currents and densities in interacting systems.…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Gianluca Stefanucci

Most applications of time-dependent density-functional theory (TDDFT) use the adiabatic local-density approximation (ALDA) for the dynamical exchange-correlation potential Vxc(r,t). An exact (i.e., nonadiabatic) extension of the…

Mesoscale and Nanoscale Physics · Physics 2015-06-25 C. A. Ullrich

Many recent applications of time-dependent density functional theory begin in an initially excited state, and propagate it using an adiabatic approximation for the exchange-correlation potential. This however inserts the excited-state…

Chemical Physics · Physics 2012-04-02 Peter Elliott , Neepa T. Maitra

Time-dependent density functional theory (TDDFT) is widely used for understanding and predicting properties and behaviors of matter. As one of the fundamental theorems in TDDFT, van Leeuwen's theorem [Phys. Rev. Lett. 82, 3863 (1999)]…

Statistical Mechanics · Physics 2024-03-08 Jiong-Hang Liang , Tian-Xing Hu , D. Wu , Zheng-Mao Sheng , J. Zhang

We propose a time-dependent approach to investigate the motion of electrons in quantum pump device configurations. The occupied one-particle states are propagated in real time and used to calculate the local electron density and current. An…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 G. Stefanucci , S. Kurth , A. Rubio , E. K. U. Gross

Quantum optimal control theory is a powerful tool for engineering quantum systems subject to external fields such as the ones created by intense lasers. The formulation relies on a suitable definition for a target functional, that…

Quantum Physics · Physics 2015-05-20 David Kammerlander , Alberto Castro , Miguel A. L. Marques

Time-dependent density functional theory has emerged as a method of choice for calculations of spectra and response properties in physics, chemistry, and biology, with its system-size scaling enabling computations on systems much larger…

Chemical Physics · Physics 2021-07-13 Neepa T. Maitra

I describe the foundation of a Density Functional Theory approach to include pairing correlations, which was applied to a variety of systems ranging from dilute fermions, to neutron stars and finite nuclei. Ground state properties as well…

Nuclear Theory · Physics 2017-08-23 Aurel Bulgac

Based on a microscopic system reservoir model,where the associated bath is not in thermal equilibrium, we simulate the nonstationary Langevin dynamics and obtained the generalized nonstationary fluctuation dissipation relation (FDR) which…

Dealing with a generic time-local non-Markovian master equation, we define current and power to be process-dependent as in classical thermodynamics. Each process is characterized by a symmetry transformation, a gauge of the master equation,…

Quantum Physics · Physics 2023-08-01 Fernando Nicacio , Raphael N. P. Maia

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

Density functional theory is discussed in the context of one-particle systems. We show that the ground state density $\rho_0(x)$ and energy $E_0$ are simply related to a family of external potential energy functions with ground state wave…

Quantum Physics · Physics 2009-11-10 H. L. Neal

The spin current density functional theory (SCDFT) is the generalization of the standard DFT to treat a fermionic system embedded in the effective external field produced by the spin-orbit coupling interaction. Even in the absence of a spin…

Adiabatic time-dependent density functional theory fails for excitations of a heteroatomic molecule composed of two open-shell fragments at large separation. Strong frequency-dependence of the exchange-correlation kernel is necessary for…

Other Condensed Matter · Physics 2009-11-11 Neepa T. Maitra , David G. Tempel

We provide a new formulation of Time-Dependent Density Functional Theory (TDDFT) based on the geometric structure of the set of states constrained to have a fixed density. Orbital-free TDDFT is formulated using a hydrodynamics equation…

We present a general formalism based on scattering theory to calculate quantum correlation functions involving several time-dependent current operators. A key ingredient is the causality of the scattering matrix, which allows one to deal…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 J. Salo , F. W. J. Hekking , J. P. Pekola

We propose a machine learning based approach to develop the exchange-correlation potential of time dependent density functional theory (TDDFT). The neural network projection from the time-varying electron densities to the corresponding…

Computational Physics · Physics 2020-05-20 Yasumitsu Suzuki , Ryo Nagai , Jun Haruyama