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Molecular absorption and photo-electron spectra can be efficiently predicted with real-time time-dependent density-functional theory (TDDFT). We show here how these techniques can be easily extended to study time-resolved pump-probe…

Atomic and Molecular Clusters · Physics 2013-01-10 Umberto De Giovannini , Gustavo Brunetto , Alberto Castro , Jessica Walkenhorst , Angel Rubio

We derive a time-dependent density functional theory appropriate for calculating the near-edge X-ray absorption spectrum in molecules and condensed matter. The basic assumption is to increase the space of many-body wave functions from one…

Strongly Correlated Electrons · Physics 2015-06-16 G. F. Bertsch , A. Lee

The projection-based quantum embedding method is applied to electronically excited states of valence, Rydberg, and charge-transfer character, valence- and core-ionized states, as well as bound and temporary radical anions. We embed…

Chemical Physics · Physics 2021-06-10 Valentina Parravicini , Thomas-C. Jagau

Nuclear Magnetic Resonance (NMR) shielding constants of transition metals in solvated complexes are computed at the relativistic density functional theory (DFT) level. The solvent effects evaluated with subsystem-DFT approaches are compared…

Chemical Physics · Physics 2021-08-09 Malgorzata Olejniczak , Andrej Antusek , Michal Jaszunski

The basic idea of Frozen-Density Embedding Theory (FDET) is the constrained minimisation of the Hohenberg-Kohn density functional $E^{HK}[\rho]$ performed using the auxiliary functional $E_{v_{AB}}^{FDET}[\Psi_A,\rho_B]$, where $\Psi_A$ is…

Chemical Physics · Physics 2020-06-22 Niccolò Ricardi , Michelle Ernst , Piero Macchi , Tomasz A. Wesolowski

Density functional theory (DFT) embedding provides a formally exact framework for interfacing correlated wave-function theory (WFT) methods with lower-level descriptions of electronic structure. Here, we report techniques to improve the…

Chemical Physics · Physics 2015-06-12 Jason D. Goodpaster , Taylor A. Barnes , Frederick R. Manby , Thomas F. Miller

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

Quantum embedding schemes have the potential to significantly reduce the computational cost of first principles calculations, whilst maintaining accuracy, particularly for calculations of electronic excitations in complex systems. In this…

Materials Science · Physics 2022-03-10 Joseph C. A. Prentice

We present an efficient and systematically convergent approach to all-electron real-time time-dependent density functional theory (TDDFT) calculations using a mixed basis, termed as enriched finite element (EFE) basis. The EFE basis…

Chemical Physics · Physics 2022-10-27 Bikash Kanungo , Nelson D. Rufus , Vikram Gavini

This paper presents some absorbing boundary conditions (ABC) for simulations based on the time-dependent density-functional theory (TDDFT). The boundary conditions are expressed in terms of the elements of the density-matrix, and it is…

Numerical Analysis · Mathematics 2019-05-01 Xiantao Li

We describe an efficient quantum embedding framework for realistic ab initio density matrix embedding (DMET) calculations in solids. We discuss in detail the choice of orbitals and mapping to a lattice, treatment of the virtual space and…

Strongly Correlated Electrons · Physics 2020-01-15 Zhi-Hao Cui , Tianyu Zhu , Garnet Kin-Lic Chan

We investigate the time an electronic excitation travels in a supermolecular setup using a measurement process in an open quantum-system framework. The approach is based on the stochastic Schr\"odinger equation and uses a Hamiltonian from…

Materials Science · Physics 2013-12-09 Dirk Hofmann , Heiko Appel , Massimiliano Di Ventra , Stephan Kümmel

Time-dependent density-functional theory (TDDFT) often successfully reproduces excitation energies of finite systems, already in the adiabatic local-density approximation (ALDA). Here we show for prototypical molecular materials, i.e.,…

Materials Science · Physics 2015-11-25 Caterina Cocchi , Claudia Draxl

A method of solving the time-dependent Schr\"odinger equation is presented, in which a finite region of space is treated explicitly, with the boundary conditions for matching the wave-functions on to the rest of the system replaced by an…

Materials Science · Physics 2009-11-13 J. E. Inglesfield

The accurate treatment of electron correlation in extended molecular systems remains computationally challenging using classical electronic structure methods. Hybrid quantum-classical algorithms offer a potential route to overcome these…

We present a formalism based on nonequilibrium dynamical mean field theory (DMFT) which allows to compute the time-resolved X-ray absorption spectrum (XAS) of photo-excited solids. By applying this formalism to the photo-doped half-filled…

Strongly Correlated Electrons · Physics 2022-10-13 Philipp Werner , Denis Golez , Martin Eckstein

This chapter provides a basic introduction to excited-state extensions of density functional theory (DFT), including time-dependent (TD-)DFT in both its linear-response and its explicitly time-dependent formulations. As applied to the…

Chemical Physics · Physics 2023-05-02 John M. Herbert

Using both time-dependent density functional theory (TDDFT) and the ``single-shot" $GW$ plus Bethe-Salpeter equation ($GW$-BSE) approach, we compute optical band gaps and optical absorption spectra from first principles for eight common…

Inspired by the formulation of quantum-electrodynamical time-dependent density functional theory (QED-TDDFT) by Rubio and coworkers, we propose an implementation that uses dimensionless amplitudes for describing the photonic contributions…

Materials Science · Physics 2021-08-20 Junjie Yang , Qi Ou , Zheng Pei , Hua Wang , Binbin Weng , Kieran Mullen , Yihan Shao

We investigate optical absorption spectra obtained through time-dependent density functional theory (TD-DFT) based on nonempirical hybrid functionals that are designed to correctly reproduce the dielectric function. The comparison with…

Materials Science · Physics 2020-08-17 Alexey Tal , Peitao Liu , Georg Kresse , Alfredo Pasquarello