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Theory can provide important support at all the stages of spectroscopic experiments, from planning the measurements to the interpretation of the results. Such support is particularly valuable for the challenging experiments on heavy,…

Atomic Physics · Physics 2025-09-19 L. F. Pašteka , E. Eliav , M. L. Reitsma , A. Borschevsky

An implementation of a complex solver for the solution of the response equations required to compute the complex response functions of damped response theory is presented for the resolution-of-identity (RI) coupled-cluster singles and…

Chemical Physics · Physics 2022-03-29 Daniil A. Fedotov , Sonia Coriani , Christof Hättig

The development of relativistic exact two-component (X2C) theory is briefly reviewed, with an emphasis on cost-effective treatments of relativistic two-electron contributions by means of model potential (MP) techniques and closely related…

Chemical Physics · Physics 2025-04-29 Xubo Wang , Chaoqun Zhang , Junzi Liu , Lan Cheng

A new method that accurately describes strongly correlated states and captures dynamical correlation is presented. It is derived as a modification of coupled-cluster theory with single and double excitations (CCSD) through consideration of…

Chemical Physics · Physics 2013-07-15 Daniel Kats , Frederick R. Manby

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

In this work, we introduce a differentiable implementation of the local natural orbital coupled cluster (LNOCC) method within the automatic differentiation framework of the PySCFAD package. The implementation is comprehensively tuned for…

Chemical Physics · Physics 2024-07-08 Xing Zhang , Chenghan Li , Hong-Zhou Ye , Timothy C. Berkelbach , Garnet Kin-Lic Chan

L-edge X-ray absorption spectra for first-row transition metal complexes are obtained from relativistic equation-of-motion singles and doubles coupled-cluster (EOM-CCSD) calculations that make use of the core-valence separation (CVS)…

We investigate the use of orbital-optimized references in conjunction with single-reference coupled-cluster theory with single and double substitutions (CCSD) for the study of core excitations and ionizations of 18 small organic molecules,…

We investigate the basis-set convergence of electronic correlation energies calculated using coupled cluster theory and a recently proposed finite basis-set correction technique. The correction is applied to atomic and molecular systems and…

Chemical Physics · Physics 2019-10-03 Andreas Irmler , Andreas Grüneis

We present an implementation of relativistic ionization-potential (IP) equation-of-motion coupled-cluster (EOMCC) with up to 3-hole--2-particle (3h2p) excitations that makes use of the molecular mean-field exact two-component (mmfX2C)…

Chemical Physics · Physics 2025-01-10 Stephen H. Yuwono , Run R. Li , Tianyuan Zhang , Xiaosong Li , A. Eugene DePrince

Linear-response quantum electrodynamical density functional theory (QEDFT) enables the description of molecular spectra under strong coupling to quantized photonic modes, such as those in optical cavities. Recently, this approach was…

Chemical Physics · Physics 2025-07-11 Lukas Konecny , Valeriia P. Kosheleva , Michael Ruggenthaler , Michal Repisky , Angel Rubio

Quantum embedding methods have recently developed significantly to model large molecular structures. This work proposes a novel wave function theory in density functional theory (WTF-in-DFT) embedding scheme based on pair-coupled cluster…

Chemical Physics · Physics 2024-01-10 Rahul Chakraborty , Katharina Boguslawski , Paweł Tecmer

The article deals with the extension of the relativistic double-ionization equation-of-motion coupled-cluster (DI-EOMCC) method [H. Pathak et al. Phys. Rev. A 90, 010501(R) (2014)] for the molecular systems. The Dirac-Coulomb (DC)…

Chemical Physics · Physics 2020-04-22 Himadri Pathak , Sudip Sasmal , Kaushik Talukdar , Malaya K. Nayak , Nayana Vaval , Sourav Pal

We present the implementation of relativistic coupled cluster quadratic response theory (QR-CC), following our development of relativistic equation of motion coupled cluster quadratic response theory (QR-EOMCC) [X. Yuan et al., J. Chem.…

Chemical Physics · Physics 2025-11-17 Xiang Yuan , Loïc Halbert , Lucas Visscher , André Severo Pereira Gomes

We present precise values of electric polarizabilities for the ground state of Zn due to second-order dipole and quadrupole interactions, and due to third-order dipole-quadrupole interactions. These quantities are evaluated in the linear…

Atomic Physics · Physics 2022-07-13 A. Chakraborty , S. K. Rithvik , B. K. Sahoo

We study the performance of spin-component-scaled second-order M{\o}ller-Plesset perturbation theory (SCS-MP2) for the prediction of the lattice constant, bulk modulus, and cohesive energy of 12 simple, three-dimensional, covalent and ionic…

Materials Science · Physics 2022-11-23 Tamar Goldzak , Xiao Wang , Hong-Zhou Ye , Timothy C. Berkelbach

The equation of motion coupled cluster singles and doubles model (EOM-CCSD) is an accurate, black-box correlated electronic structure approach to investigate electronically excited states and electron attachment or detachment processes. It…

Chemical Physics · Physics 2023-09-18 Loïc Halbert , Andre Severo Pereira Gomes

Relativistic coupled-cluster (RCC) theory at the singles and doubles approximation has been implemented to estimate nuclear spin dependent (NSD) parity violating (PV) electric dipole (E1) transition amplitudes ($E1_{PV}^{NSD}$) among…

Atomic Physics · Physics 2024-08-19 A. Chakraborty , B. K. Sahoo

Tailored coupled cluster theory represents a computationally inexpensive way to describe static and dynamical electron correlation effects. In this work, we scrutinize the performance of various tailored coupled cluster methods externally…

Chemical Physics · Physics 2021-03-24 Aleksandra Leszczyk , Mihály Máté , Örs Legeza , Katharina Boguslawski

The coupled-cluster method is applied to the spin-1/2 antiferromagnetic XXZ model on a square lattice by employing an approximation which contains two-body long-range correlations and high-order four-body local correlations. Improvement is…

Strongly Correlated Electrons · Physics 2015-05-28 Mohammad Merdan , Y. Xian