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The time-dependent exchange-correlation potential has an unusual task in directing fictitious non-interacting electrons to move with exactly the same probability density as true interacting electrons. This has intriguing implications for…

Chemical Physics · Physics 2024-06-19 Davood Dar , Lionel Lacombe , Neepa T. Maitra

Recent work showed that the exact exchange-correlation potential of time-dependent density functional theory generically displays dynamical step structures. These have a spatially non-local and time-non-local dependence on the density in…

Chemical Physics · Physics 2013-12-09 K. Luo , P. Elliott , N. T. Maitra

Knowledge of exact properties of the exchange-correlation (xc) functional is important for improving the approximations made within density functional theory. Features such as steps in the exact xc potential are known to be necessary for…

Strongly Correlated Electrons · Physics 2021-01-15 M. J. P. Hodgson , J. D. Ramsden , R. W. Godby

We present a new class of non-adiabatic approximations in time-dependent density functional theory derived from an exact expression for the time-dependent exchange-correlation potential. The approximations reproduce dynamical step and peak…

Chemical Physics · Physics 2018-12-21 Lionel Lacombe , Neepa T. Maitra

We show that as an electron transfers between closed-shell molecular fragments at large separation, the exact correlation potential of time-dependent density functional theory gradually develops a step and peak structure in the bonding…

Chemical Physics · Physics 2014-02-11 Johanna I. Fuks , Peter Elliott , Angel Rubio , Neepa T. Maitra

The exact exchange-correlation (xc) potential of time-dependent density functional theory has been shown to have striking features. For example, step and peak features are generically found when the system is far from its ground-state, and…

Chemical Physics · Physics 2014-03-11 Kai Luo , Johanna I. Fuks , Ernesto D. Sandoval , Peter Elliott , Neepa T. Maitra

We identify peak and valley structures in the exact exchange-correlation potential of time-dependent density functional theory that are crucial for time-resolved electron scattering in a model one-dimensional system. These structures are…

Chemical Physics · Physics 2018-01-03 Yasumitsu Suzuki , Lionel Lacombe , Kazuyuki Watanabe , Neepa T. Maitra

We employ the density matrix renormalization group to construct the exact time-dependent exchange correlation potential for an impurity model with an applied transport voltage. Even for short-ranged interaction we find an infinitely…

Mesoscale and Nanoscale Physics · Physics 2017-09-13 Peter Schmitteckert , Michael Dzierzawa , Peter Schwab

The exact exchange potential in time-dependent density-functional theory is defined as an orbital functional through the time-dependent optimized effective potential (TDOEP) method. We numerically solve the TDOEP integral equation for the…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 H. O. Wijewardane , C. A. Ullrich

Time-dependent density functional theory continues to draw a large number of users in a wide range of fields exploring myriad applications involving electronic spectra and dynamics. Although in principle exact, the predictivity of the…

Chemical Physics · Physics 2023-08-14 Lionel Lacombe , Neepa T. Maitra

We simulate the dynamics of a single-electron source, modeled as a quantum dot with on-site Coulomb interaction and tunnel coupling to an adjacent lead, in time-dependent density functional theory. Based on this system, we develop a…

Mesoscale and Nanoscale Physics · Physics 2018-04-18 Niklas Dittmann , Janine Splettstoesser , Nicole Helbig

We propose a practical approximation to the exchange-correlation functional of (time-dependent) density functional theory for many-electron systems coupled to photons. The (time non-local) optimized effective potential (OEP) equation for…

Mesoscale and Nanoscale Physics · Physics 2015-09-02 Camilla Pellegrini , Johannes Flick , Ilya V. Tokatly , Heiko Appel , Angel Rubio

It was recently shown [Y. Suzuki, L. Lacombe, K. Watanabe, and N. T. Maitra, Phys. Rev. Lett. 119, 263401 (2017)] that peak and valley structures in the exact exchange-correlation potential of time-dependent density functional theory are…

Chemical Physics · Physics 2018-07-04 Lionel Lacombe , Yasumitsu Suzuki , Kazuyuki Watanabe , Neepa T. Maitra

Most approximate exchange-correlation functionals used within density functional theory are constructed as the sum of two distinct contributions for exchange and correlation. Separating the exchange component from the entire functional is…

Condensed Matter · Physics 2009-10-28 Claudia Filippi , C. J. Umrigar , Xavier Gonze

Charge transfer plays a crucial role in many processes of interest in physics, chemistry, and bio-chemistry. In many applications the size of the systems involved calls for time-dependent density functional theory (TDDFT) to be used in…

Chemical Physics · Physics 2017-10-11 Neepa T. Maitra

We consider electronic exchange and correlation effects in density-functional calculations of two-dimensional systems. Starting from wave function calculations of total energies and electron densities of inhomogeneous model systems, we…

Mesoscale and Nanoscale Physics · Physics 2012-05-30 Ilja Makkonen , Mikko M. Ervasti , Ville Kauppila , Ari Harju

In order to assess the accuracy of commonly used approximate exchange-correlation density functionals, we present a comparison of accurate exchange and correlation potentials, exchange energy densities and energy components with the…

Condensed Matter · Physics 2007-05-23 Claudia Filippi , Xavier Gonze , C. J. Umrigar

A decomposition of the exact exchange-correlation potential of time-dependent density functional theory into an interaction component and a kinetic component offers a new starting point for non- adiabatic approximations. The components are…

Chemical Physics · Physics 2018-11-14 Johanna I. Fuks , Lionel Lacombe , Soeren E. B. Nielsen , Neepa T. Maitra

We train a neural network as the universal exchange-correlation functional of density-functional theory that simultaneously reproduces both the exact exchange-correlation energy and potential. This functional is extremely non-local, but…

Computational Physics · Physics 2019-10-10 Jonathan Schmidt , Carlos L. Benavides-Riveros , Miguel A. L. Marques

It has been known for some time that the exchange-correlation potential in time-dependent density functional theory is an intrinsically nonlocal functional of the density as soon as one goes beyond the adiabatic approximation. In this paper…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Z. Qian , A. Constantinescu , G. Vignale
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