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We developed a general framework for hybrid quantum-classical computing of molecular and periodic embedding approaches based on an orbital space separation of the fragment and environment degrees of freedom. We demonstrate its potential by…

Chemical Physics · Physics 2024-12-23 Stefano Battaglia , Max Rossmannek , Vladimir V. Rybkin , Ivano Tavernelli , Jürg Hutter

A multiscale QM/classical approach is presented, that is able to model the optical properties of complex nanostructures composed of a molecular system adsorbed on metal nanoparticles. The latter are described by a combined…

Chemical Physics · Physics 2024-10-29 Pablo Grobas Illobre , Piero Lafiosca , Luca Bonatti , Tommaso Giovannini , Chiara Cappelli

We present an embedding approach to treat local electron correlation effects in periodic environments. In a single, consistent framework, our plane-wave based scheme embeds a local high-level correlation calculation (here Coupled Cluster…

Chemical Physics · Physics 2021-01-07 Tobias Schäfer , Florian Libisch , Georg Kresse , Andreas Grüneis

We present a mixed basis-set approach to obtain optical absorption spectra within a generalized Kohn-Sham time-dependent density functional theory framework. All occupied valence molecular orbitals (MOs) are expanded in a plane-wave (PW)…

Chemical Physics · Physics 2025-08-13 Kyle Chen , Barry Y. Li , Tucker Allen , Daniel Neuhauser

A scheme for active temporal-to-spatial demultiplexing of single-photons generated by a solid-state source is introduced. The scheme scales quasi-polynomially with photon number, providing a viable technological path for routing n photons…

The coherent two-dimensional (2D) electronic spectra with respect to the singlet fission (SF) process in organic molecular aggregates are simulated by the Davydov ansatz combined with the Frenkel-Dirac time-dependent variational algorithm.…

Mesoscale and Nanoscale Physics · Physics 2018-01-17 Ke-Wei Sun , Yao Yao

Theoretical spectroscopy, and more generally, electronic-structure theory, are powerful concepts for describing the complex many-body interactions in materials. They comprise a variety of methods that can capture all aspects, from…

Density matrix embedding theory (DMET) [Phys. Rev. Lett., 109, 186404 (2012)], introduced a new approach to quantum cluster embedding methods, whereby the mapping of strongly correlated bulk problems to an impurity with finite set of bath…

Strongly Correlated Electrons · Physics 2015-06-24 George H. Booth , Garnet Kin-Lic Chan

We extend the concepts of the Autler-Townes doublet and triplet spectroscopy to quartuplet, quintuplet and suggest linkages in sodium atom in which to display these spectra. We explore the involved fundamental processes of quantum…

Quantum Physics · Physics 2015-06-15 Fazal Ghafoor

An easily accessible method is presented that permits to calculate spectra involving atomic multiplets relevant to X-ray Absorption Spectroscopy (XAS) and Resonant Inelastic X-ray Scattering (RIXS) experiments. We present specific examples…

Strongly Correlated Electrons · Physics 2009-03-16 F. Vernay , B. Delley

We present an efficient implementation of the Bethe-Salpeter equation (BSE) method for obtaining core-level spectra including x-ray absorption (XAS), x-ray emission (XES), and both resonant and non-resonant inelastic x-ray scattering…

Computational Physics · Physics 2016-01-29 K. Gilmore , John Vinson , E. L. Shirley , D. Prendergast , C. D. Pemmaraju , J. J. Kas , F. D. Vila , J. J. Rehr

We present an approach that combines the local density approximation (LDA) and the dynamical mean-field theory (DMFT) in the framework of the full-potential linear augmented plane waves (FLAPW) method. Wannier-like functions for the…

The Bethe-Salpeter equation for the electron-hole correlation function is the state-of-the-art formalism for optical and core spectroscopy in condensed matter. Solutions of this equation yield the full dielectric response, including both…

Materials Science · Physics 2019-04-12 Christian Vorwerk , Benjamin Aurich , Caterina Cocchi , Claudia Draxl

Broadly speaking, the calculation of core spectra such as electron energy loss spectra (EELS) at the level of density functional theory (DFT) usually relies one of two approaches: conceptually more complex but computationally efficient…

Embedding techniques allow the efficient description of correlations within localized fragments of large molecular systems, while accounting for their environment at a lower level of theory. We introduce FragPT2: a novel embedding framework…

Chemical Physics · Physics 2025-01-15 Emiel Koridon , Souloke Sen , Lucas Visscher , Stefano Polla

In this work, we present a computationally efficient methodology that utilizes a local real-space formulation of the projector augmented wave (PAW) method discretized with a finite-element (FE) basis to enable accurate and large-scale…

Computational Physics · Physics 2025-01-03 Kartick Ramakrishnan , Sambit Das , Phani Motamarri

In the fields of brain-computer interaction and cognitive neuroscience, effective decoding of auditory signals from task-based functional magnetic resonance imaging (fMRI) is key to understanding how the brain processes complex auditory…

Neurons and Cognition · Quantitative Biology 2024-06-05 Wanli Ma , Xuegang Tang , Jin Gu , Ying Wang , Yuling Xia

Covariant density functional theory, which has so far been applied only within the framework of static and time dependent mean field theory is extended to include Particle-Vibration Coupling (PVC) in a consistent way. Starting from a…

Nuclear Theory · Physics 2008-11-26 E. Litvinova , P. Ring , V. Tselyaev

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

The treatment of electronic correlations in open-shell systems is among the most challenging problems of condensed matter theory. Current approximations are only partly successful. Ligand field multiplet theory (LFMT) has been widely…

Materials Science · Physics 2022-06-08 J. J. Kas , J. J. Rehr , T. P. Devereaux
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