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Quantum-selected configuration interaction (QSCI) is a novel quantum-classical hybrid algorithm for quantum chemistry calculations. This method identifies electron configurations having large weights for the target state using quantum…

Chemical Physics · Physics 2025-03-31 Soichi Shirai , Shih-Yen Tseng , Hokuto Iwakiri , Takahiro Horiba , Hirotoshi Hirai , Sho Koh

We study the structural effects produced by the quantization of vibrational degrees of freedom in periodic crystals at zero temperature. To this end we introduce a methodology based on mapping a suitable subspace of the vibrational manifold…

Materials Science · Physics 2009-11-13 I. Scivetti , N. I. Gidopoulos , J. Kohanoff

By combining Hartree-Fock with a neural-network-supported quantum-cluster solver proposed recently in the context of solid-state lattice models, we formulate a scheme for selective neural-network configuration interaction (NNCI)…

We propose a novel partitioning of the Hilbert space, hierarchy configuration interaction (hCI), where the excitation degree (with respect to a given reference determinant) and the seniority number (i.e., the number of unpaired electrons)…

Chemical Physics · Physics 2022-05-12 Fábris Kossoski , Yann Damour , Pierre-François Loos

In this paper, we study the nuclear gradients of heat bath configuration interaction self-consistent field (HCISCF) wave functions and use them to optimize molecular geometries for various molecules. We show that the HCISCF nuclear…

Chemical Physics · Physics 2022-09-14 James E. T. Smith , Joonho Lee , Sandeep Sharma

Quantum-selected configuration interaction (QSCI) is an approach for quantum chemical calculations using current quantum computers. In conventional QSCI, Slater determinants used for the wave function expansion are sampled by iteratively…

Quantum Physics · Physics 2025-10-03 Kenji Sugisaki , Shu Kanno , Toshinari Itoko , Rei Sakuma , Naoki Yamamoto

High-level vibrational calculations have been used to investigate anharmonicity in a wide variety of materials using density-functional-theory (DFT) methods. We have developed a new and efficient approach for describing strongly-anharmonic…

Materials Science · Physics 2017-06-20 Joseph C. A. Prentice , R. J. Needs

Quantum computation of vibrational properties of molecules is a promising platform to obtain computational advantages for computational chemistry. However, fault-tolerant quantum computations of vibrational properties remain a relatively…

A time-dependent vibrational electronic coupled-cluster (VECC) approach is proposed to simulate photoelectron/ UV-VIS absorption spectra, as well as time-dependent properties for non-adiabatic vibronic models, going beyond the…

Chemical Physics · Physics 2023-12-25 Songhao Bao , Neil Raymond , Marcel Nooijen

We present a simple and efficient method to incorporate anharmonic effects in the vibrational \textcolor{black}{analyses} of molecules within density functional theory (DFT) calculations. This approach is closely related to the traditional…

Hierarchy configuration interaction (hCI) has been recently introduced as an alternative configuration interaction (CI) route combining excitation degree and seniority number, which showed to efficiently recover both dynamic and static…

Chemical Physics · Physics 2024-02-20 Fábris Kossoski , Pierre-François Loos

An accurate description of electron correlation is one of the most challenging problems in quantum chemistry. The exact electron correlation can be obtained by means of full configuration interaction (FCI). A simple strategy for…

Chemical Physics · Physics 2021-05-14 Jae Woo Park

Addressing both dynamic and static correlation accurately is a primary goal in electronic structure theory. Non-orthogonal configuration interaction (NOCI) is a versatile tool for treating static correlation, offering chemical insights by…

Chemical Physics · Physics 2025-06-27 Chong Sun , Fei Gao , Gustavo E. Scuseria

Recent advances in selected CI, including the adaptive sampling configuration interaction (ASCI) algorithm and its heat bath extension, have made the ASCI approach competitive with the most accurate techniques available, and hence an…

We propose the concept of machine learning configuration interaction (MLCI) whereby an artificial neural network is trained on-the-fly to predict important new configurations in an iterative selected configuration interaction procedure. We…

Chemical Physics · Physics 2018-10-18 J. P. Coe

Understanding the mechanism of chemical reaction rate modulation by vibrational strong coupling (VSC) has been the focus of several recent studies. However, a definitive explanation for the mode-specificity of VSC still eludes us. In this…

Chemical Physics · Physics 2026-03-11 Subhadip Mondal , Atul Kumar , Srihari Keshavamurthy

Background: Ab initio many-body methods have been developed over the past ten years to address mid-mass nuclei... As progress in the design of inter-nucleon interactions is made, further efforts must be made to tailor many-body methods.…

Nuclear Theory · Physics 2017-02-01 J. Ripoche , D. Lacroix , D. Gambacurta , J. -P. Ebran , T. Duguet

We give a thorough analysis of the convergence properties of the configuration-interaction method as applied to parabolic quantum dots among other systems, including \emph{a priori} error estimates. The method converges slowly in general,…

Computational Physics · Physics 2013-05-29 Simen Kvaal

The computationally expensive evaluation and storage of high-rank reduced density matrices (RDMs) has been the bottleneck in the calculation of dynamic correlation for multireference wave functions in large active spaces. We present a…

Chemical Physics · Physics 2020-01-08 Ankit Mahajan , Nick S. Blunt , Iliya Sabzevari , Sandeep Sharma

We introduce the pCI software package for high-precision atomic structure calculations. The standard method of calculation is based on the configuration interaction (CI) method to describe valence correlations, but can be extended to attain…