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Small-scale plasticity problems are often characterised by different patterning behaviours ranging from macroscopic down to the atomistic scale. In successful models of such complex behaviour, its origin lies within non-convexity of the…

Computational Physics · Physics 2018-11-01 F. Bormann , R. H. J. Peerlings , M. G. D. Geers

We present a natural orbital-based implementation of the intermediate Hamiltonian Fock space coupled-cluster method for (1,1) sector of Fock space. The use of natural orbital significantly reduces the computational cost and can…

Chemical Physics · Physics 2021-09-07 Soumi Haldar , Achintya Kumar Dutta

DC Optimal Power Flow (DC-OPF) problems optimize the generators' active power setpoints while satisfying constraints based on the DC power flow linearization. The computational tractability advantages of DC-OPF problems come at the expense…

Optimization and Control · Mathematics 2025-12-23 Babak Taheri , Daniel K. Molzahn

Coupled cluster methods based exclusively on double excitations are comparatively "cheap" and interesting model chemistries, as they are typically able to capture the bulk of the dynamical electron correlation effects. The trade-off in such…

Quantum Physics · Physics 2024-06-14 Zachary W. Windom , Daniel Claudino , Rodney J. Bartlett

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

An efficient O($N$) divide-conquer (DC) method based on localized natural orbitals (LNOs) is presented for large-scale density functional theories (DFT) calculations of gapped and metallic systems. The LNOs are non-iteratively calculated by…

Computational Physics · Physics 2019-01-02 Taisuke Ozaki , Masahiro Fukuda , Gengping Jiang

We present the theory and the implementation of a low-cost four-component relativistic equation of motion coupled cluster method for ionized states based on frozen natural spinors. A single threshold (natural spinor occupancy) can control…

Chemical Physics · Physics 2024-06-19 Kshitijkumar Surjuse , Somesh Chamoli , Malaya K. Nayak , Achintya Kumar Dutta

An efficiency of the Tucker decomposition of amplitude tensors within the single-reference relativistic coupled cluster method with single and double excitations (RCCSD) was studied in a series of benchmark calculations for (AuCl)$_n$…

Computational Physics · Physics 2025-07-29 Alexander V. Oleynichenko , Artem S. Rumiantsev , Andrei Zaitsevskii , Ephraim Eliav

We present the theory, implementation, and benchmark results for a frozen natural spinors-based lower scaling four-component relativistic coupled cluster method. The natural spinors are obtained by diagonalizing the one-body reduced density…

Chemical Physics · Physics 2022-06-15 Somesh Chamoli , Kshitijkumar Surjuse , Malaya K. Nayak , Achintya Kumar Dutta

Numerous numerical studies have shown that geminal-based methods are a promising direction to model strongly correlated systems with low computational costs. Several strategies have been introduced to capture the missing dynamical…

Chemical Physics · Physics 2023-03-22 Artur Nowak , Katharina Boguslawski

The Poisson--Nernst--Planck (PNP) equations have been widely applied to describe ionic transport in ion channels, nanofluidic devices, and many electrochemical systems. Despite their wide applications, the PNP equations fail in predicting…

Statistical Mechanics · Physics 2018-01-03 Farjana Siddiqua , Zhongming Wang , Shenggao Zhou

Advances in artificial intelligence (AI) and deep learning have raised concerns about its increasing energy consumption, while demand for deploying AI in mobile devices and machines at the edge is growing. Binary neural networks (BNNs) have…

Optimization and Control · Mathematics 2026-01-05 Jonas Christoffer Villumsen , Yusuke Sugita

We introduce a novel algorithm that leverages stochastic sampling techniques to compute the perturbative triples correction in the coupled-cluster (CC) framework. By combining elements of randomness and determinism, our algorithm achieves a…

Chemical Physics · Physics 2024-05-29 Yann Damour , Alejandro Gallo , Anthony Scemama

We present a perturbative triples correction to the relativistic quadratic unitary coupled cluster singles and doubles (qUCCSD) method, denoted as qUCCSD[T]. The method builds upon the Hermitian structure of the unitary ansatz and employs a…

Chemical Physics · Physics 2025-10-08 Kamal Majee , Ján Šimunek , Jozef Noga , Achintya Kumar Dutta

The focus of this work is OS-CCSD-SPT(2), which is a second-order similarity transformed perturbation theory correction to opposite spin coupled cluster singles doubles, where in the latter the same-spin amplitudes are removed and the…

Chemical Physics · Physics 2020-03-16 David W. Small

The ionization potential (IP) is an important parameter providing essential insights into the reactivity of chemical systems. IPs are also crucial for designing, optimizing, and understanding the functionality of modern technological…

Chemical Physics · Physics 2024-02-12 Marta Gałyńska , Katharina Boguslawski

We present the working equations for a reduced-scaling method of evaluating the perturbative triples (T) energy in coupled-cluster theory, through the tensor hypercontraction (THC) of the triples amplitudes ($t_{ijk}^{abc}$). Through our…

Chemical Physics · Physics 2024-06-12 Andy Jiang , Justin M. Turney , Henry F. Schaefer

We study the application of various forms of the coupled cluster method to systems with paired fermions. The novel element of the analysis is the study of the breaking and eventual restoration of particle number in the CCM variants. We…

Quantum Physics · Physics 2010-11-24 Chris Snape , Niels R. Walet

We present a quantum linear response (qLR) approach within an active-space framework for computing indirect nuclear spin-spin coupling constants, a key ingredient in NMR spectra predictions. The method employs the unitary coupled cluster…

We present the theoretical framework, implementation, and benchmark results for a reduced-cost relativistic equation-of-motion coupled cluster singles and doubles (EOM-CCSD) method based on state-specific frozen natural spinors (SS-FNS). In…