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In this work we describe the rank-reduced variant of the equation-of-motion coupled cluster theory with complete inclusion of single, double, and triple excitations. The advantage of the proposed formalism in comparison with the canonical…

Chemical Physics · Physics 2026-05-15 Piotr Michalak , Michał Lesiuk

The first nonperturbative version of the multireference driven similarity renormalization group (MR-DSRG) theory [C. Li and F. A. Evangelista, J. Chem. Theory Comput. $\mathbf{11}$, 2097 (2015)] is introduced. The renormalization group…

Chemical Physics · Physics 2016-05-25 Chenyang Li , Francesco A. Evangelista

The extension of mixed quantum/classical theory (MQCT) to describe collisional energy transfer is developed for symmetric-top-rotor + linear-rotor system type and is applied to $ \rm ND_3 + \rm D_2 $. State-to-state transition cross…

Chemical Physics · Physics 2023-07-19 Carolin Joy , Bikramaditya Mandal , Dulat Bostan , Dmitri Babikov

A comprehensive and detailed account is presented for the finite-temperature many-body perturbation theory for electrons that expands in power series all thermodynamic functions on an equal footing. Algebraic recursions in the style of the…

Statistical Mechanics · Physics 2021-09-21 So Hirata

The present paper introduces a new multi-reference perturbation approach developed at second order, based on a Jeziorsky-Mokhorst expansion using individual Slater determinants as perturbers. Thanks to this choice of perturbers, an…

Chemical Physics · Physics 2017-06-28 Emmanuel Giner , Celestino Angeli , Yann Garniron , Anthony Scemama , Jean-Paul Malrieu

Many-body techniques based on the double unitary coupled cluster ansatz (DUCC) can be used to downfold electronic Hamiltonians into low-dimensional active spaces. It can be shown that the resulting dimensionality reduced Hamiltonians are…

Quantum Physics · Physics 2020-01-29 Nicholas P. Bauman , Guang Hao Low , Karol Kowalski

We present a formulation of the multiconfigurational (MC) wave function symmetry-adapted perturbation theory (SAPT). The method is applicable to noncovalent interactions between monomers which require a multiconfigurational description, in…

Chemical Physics · Physics 2021-04-15 Michal Hapka , Michal Przybytek , Katarzyna Pernal

This article presents an alternative formulation of quasi-degenerate perturbation theory (QDPT). The development results by simplifying established many-body (MB) techniques to systems of non-interacting particles (NIP). While the physical…

Chemical Physics · Physics 2023-09-28 Jochen Schirmer

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

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

Recent work from our research group has demonstrated that symmetry-projected Hartree--Fock (HF) methods provide a compact representation of molecular ground state wavefunctions based on a superposition of non-orthogonal Slater determinants.…

Chemical Physics · Physics 2015-06-17 Carlos A. Jiménez-Hoyos , R. Rodríguez-Guzmán , Gustavo E. Scuseria

We present a scalable machine learning (ML) model to predict local electronic properties such as on-site electron number and double occupation for disordered correlated electron systems. Our approach is based on the locality principle, or…

Strongly Correlated Electrons · Physics 2022-08-31 Yi-Hsuan Liu , Sheng Zhang , Puhan Zhang , Ting-Kuo Lee , Gia-Wei Chern

The choice of the electronic representation in on-the-fly quantum dynamics is crucial. The adiabatic representation is appealing since adiabatic states are readily available from quantum chemistry packages. The nuclear wavepackets are then…

Chemical Physics · Physics 2022-05-03 Rosa Maskri , Loïc Joubert-Doriol

In this work, an advanced motion controller is proposed for buck converter-fed DC motor systems. The design is based on an idea of active disturbance rejection control (ADRC) with its key component being a custom observer capable of…

Systems and Control · Electrical Eng. & Systems 2020-12-08 Rafal Madonski , Krzysztof Łakomy , Momir Stankovic , Sally Shao , Jun Yang , Shihua Li

Density functional theory (DFT) based modeling of electronic excited states is of importance for investigation of the photophysical/photochemical properties and spectroscopic characterization of large systems. The widely used linear…

Chemical Physics · Physics 2021-05-11 Diptarka Hait , Martin Head-Gordon

Adaptive Mixed-Criticality (AMC) is a fixed-priority preemptive scheduling algorithm for mixed-criticality hard real-time systems. It dominates many other scheduling algorithms for mixed-criticality systems, but does so at the cost of…

Operating Systems · Computer Science 2024-11-04 Bruno Mendes , Pedro F. Souto , Pedro C. Diniz

Analytic gradient routines are a desirable feature for quantum mechanical methods, allowing for efficient determination of equilibrium and transition state structures and several other molecular properties. In this work, we present…

Chemical disorder, originating from the mixed occupation of crystallographic sites by multiple elements, is widespread in alloys, ceramics, and compositionally complex materials, where short- and long-range orderings can strongly influence…

Materials Science · Physics 2026-05-20 Jiayu Peng , Peichen Zhong

We introduce a novel computational approach for the investigation of complex correlated electron materials which makes it possible to evaluate interatomic forces and thereby determine atomic displacements and structural transformations…

Strongly Correlated Electrons · Physics 2014-04-24 I. Leonov , V. I. Anisimov , D. Vollhardt

The versatile Arbitrary-DERivative (ADER) scheme is cast in a multilevel framework (ML-ADER) for fast solution of system of linear hyperbolic partial differential equations. The solution is cycled through spatial operators of varying…

Computational Physics · Physics 2017-04-05 S. M. Joshi , A. Chatterjee