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While providing a highly accurate framework for simulating laser-induced many-electron dynamics in atom and molecules, including linear and nonlinear steady-state and transient absorption spectra, time-dependent coupled-cluster theory does…

We apply a mixed quantum-classical (MQC) approach to the quantum Rabi model, involving a classical optical field coupled self-consistently to a quantum two-level system. Under the rotating wave approximation, we analytically show this…

Quantum Physics · Physics 2025-06-13 Ming-Hsiu Hsieh , Roel Tempelaar

Time crystals, a unique non-equilibrium quantum phenomenon with promising applications in current quantum technologies, mark a significant advance in quantum mechanics. Although traditionally studied in atom-cavity and optical lattice…

Quantum Physics · Physics 2024-10-07 Subhajit Sarkar , Yonatan Dubi

The tailored coupled cluster (TCC) approach is a promising ansatz that preserves the simplicity of single-reference coupled cluster theory, while incorporating a multi-reference wave function through amplitudes obtained from a preceding…

Chemical Physics · Physics 2021-01-07 Maximilian Mörchen , Leon Freitag , Markus Reiher

The primary computational challenge when simulating nonadiabatic ab initio molecular dynamics is the unfavorable compute costs of electronic structure calculations with molecular size. Simple electronic structure theories, like…

Chemical Physics · Physics 2023-06-28 Justin J. Talbot , Martin Head-Gordon , Stephen J. Cotton

We study time-dependent coupled-cluster theory in the framework of nuclear physics. Based on Kvaal's bi-variational formulation of this method [S. Kvaal, arXiv:1201.5548], we explicitly demonstrate that observables that commute with the…

Nuclear Theory · Physics 2012-07-04 D. A. Pigg , G. Hagen , H. Nam , T. Papenbrock

Compared with time independent Hamiltonians, the dynamics of generic quantum Hamiltonians $H(t)$ are complicated by the presence of time ordering in the evolution operator. In the context of digital quantum simulation, this difficulty…

Quantum Physics · Physics 2024-04-08 Jacob Watkins , Nathan Wiebe , Alessandro Roggero , Dean Lee

Subsequence clustering of multivariate time series is a useful tool for discovering repeated patterns in temporal data. Once these patterns have been discovered, seemingly complicated datasets can be interpreted as a temporal sequence of…

Machine Learning · Computer Science 2018-05-16 David Hallac , Sagar Vare , Stephen Boyd , Jure Leskovec

We report the implementation of equation-of-motion coupled-cluster (EOMCC) method in the four-component relativistic framework with the spherical atomic potential to generate the excited states from a closed-shell atomic configuration. This…

Atomic Physics · Physics 2015-06-19 D. K. Nandy , Yashpal Singh , B. K. Sahoo

In single-reference coupled-cluster (CC) methods, one has to solve a set of non-linear polynomial equations in order to determine the so-called amplitudes which are then used to compute the energy and other properties. Although it is of…

Chemical Physics · Physics 2021-09-10 Antoine Marie , Fábris Kossoski , Pierre-François Loos

In quantum chemistry, one of the most important challenges is the static correlation problem when solving the electronic Schr\"odinger equation for molecules in the Born--Oppenheimer approximation. In this article, we analyze the tailored…

Numerical Analysis · Mathematics 2019-11-21 Fabian M. Faulstich , Andre Laestadius , Örs Legeza , Reinhold Schneider , Simen Kvaal

In order to explore the effects of high levels of electron correlation on the real-time coupled cluster formalism and algorithmic behavior, we introduce a time-dependent implementation of the CC3 singles, doubles and approximate triples…

Chemical Physics · Physics 2025-01-23 Zhe Wang , Håkon Emil Kristiansen , Thomas Bondo Pedersen , T. Daniel Crawford

Cluster synchronization is a fundamental phenomenon in systems of coupled oscillators. Here, we investigate clustering patterns that emerge in a unidirectional ring of four delay-coupled electrochemical oscillators. A voltage parameter in…

Dynamical Systems · Mathematics 2023-06-28 Andrew Keane , Alannah Neff , Karen Blaha , Andreas Amann , Philipp Hövel

A model cluster, with a resonant electron spin surrounded with identical nuclear spins occupying the sites of a cubic lattice, and with dipolar coupling between the spins, is used for a theoretical investigation of the transient nutations…

Quantum Physics · Physics 2017-01-25 Alain Deville , Anne-Marie Daré , Julien Azema

A numerical scheme for solving the time-evolution of wave functions under the time dependent Kohn-Sham equation has been developed. Since the effective Hamiltonian depends on the wave functions, the wave functions and the effective…

Computational Physics · Physics 2009-11-07 Naoki Watanabe , Masaru Tsukada

In this work we present a coupled-cluster theory for the propagation of multireference electronic systems initiating at general quantum mechanical states. Our formalism is based on the infinitesimal analysis of modified cluster operators,…

Chemical Physics · Physics 2025-05-09 Martín A. Mosquera

A dynamical formulation of coupled cluster theory is derived using a variational principle. By allowing time-dependent single-particle functions, a high degree of adaptivity is introduced, allowing complex systems to be simulated with high…

Quantum Physics · Physics 2014-11-25 Simen Kvaal

A stochastic approach to time-dependent density functional theory (TDDFT) is developed for computing the absorption cross section and the random phase approximation (RPA) correlation energy. The core idea of the approach involves…

Chemical Physics · Physics 2016-11-04 Yi Gao , Daniel Neuhauser , Roi Baer , Eran Rabani

The Coupled Cluster (CC) method is used to compute the electronic correlation energy in atoms and molecules and often leads to highly accurate results. However, due to its single-reference nature, standard CC in its projected form fails to…

Accurately resolving many-body satellite features in molecular core-level spectra requires theoretical approaches that capture electron correlation both efficiently and systematically. The recently developed time-dependent double…

Quantum Physics · Physics 2026-05-12 Vibin Abraham , Priyabrata Senapati , Himadri Pathak , Bo Peng