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Quantum computing opens up new possibilities for the simulation of many-body nuclear systems. As the number of particles in a many-body system increases, the size of the space if the associated Hamiltonian increases exponentially. This…

Quantum Physics · Physics 2022-09-19 Isaac Hobday , Paul Stevenson , James Benstead

We propose a variational scheme to represent composite quantum systems using multiple parameterized functions of varying accuracies on both classical and quantum hardware. The approach follows the variational principle over the entire…

Quantum Physics · Physics 2024-06-21 Stefano Barison , Filippo Vicentini , Giuseppe Carleo

We propose a descriptor for molecular electronic structure that is based solely on the one- and two-electron integrals but is translationally, rotationally, and unitarily invariant. Then, directly exploiting size consistency, we train and…

Quantum Physics · Physics 2026-03-02 Valerii Chuiko , Giovanni B. Da Rosa , Paul W. Ayers

An overview of quantum-mechanical methods to generate cross-section data for electron collisions with atoms and molecules is presented. Particular emphasis is placed on the time-independent close-coupling approach, since it is particularly…

Plasma Physics · Physics 2016-10-21 Klaus Bartschat , Jonathan Tennyson , Oleg Zatsarinny

We present a method for the calculation of electronic structure of systems that contain tens of thousands of atoms. The method is based on the division of the system into mutually overlapping fragments and the representation of the…

Materials Science · Physics 2011-03-09 Nenad Vukmirović , Lin-Wang Wang

Publicly available collections of drug-like molecules have grown to comprise 10s of billions of possibilities in recent history due to advances in chemical synthesis. Traditional methods for identifying "hit" molecules from a large…

A hierarchy of wavefunction composite methods (cWFT), based on G4- type cWFT methods available for elements H through Rn, was recently reported by Semidalas and Martin [J. Chem. Theor. Comput. 2020, 16, 4238]. We extend this hierarchy by…

Chemical Physics · Physics 2021-02-09 Emmanouil Semidalas , Jan M. L. Martin

We introduce a theory that exposes the fundamental and previously overlooked connection between the correlation among electrons and the degree of quantum coherence of electronic states in matter. For arbitrary states, the effects only…

Quantum Physics · Physics 2016-04-21 Arnab Kar , Liping Chen , Ignacio Franco

Potential energy surfaces of the hydrogen molecular ion H$_2^+$ in the Born-Oppenheimer approximation are computed by means of the Riccati-Pad\'e method (RPM). The convergence properties of the method are analyzed for different states. The…

Chemical Physics · Physics 2022-10-25 Francisco Marcelo Fernández , Javier Garcia

Atomic basis sets are widely employed within quantum mechanics based simulations of matter. We introduce a machine learning model that adapts the basis set to the local chemical environment of each atom, prior to the start of self…

Chemical Physics · Physics 2024-04-29 Danish Khan , Maximilian L. Ach , O. Anatole von Lilienfeld

Multireference electron correlation methods describe static and dynamical electron correlation in a balanced way, and therefore, can yield accurate and predictive results even when single-reference methods or multiconfigurational…

Chemical Physics · Physics 2019-11-19 Jae Woo Park , Rachael Al-Saadon , Matthew K. MacLeod , Toru Shiozaki , Bess Vlaisavljevich

This paper introduces a new representation method that is mainly based on chemical bonds among atoms in materials. Each chemical bond and its surrounded atoms are considered as a unified unit or a local structure that is expected to reflect…

Materials Science · Physics 2018-01-03 Van-Doan Nguyen , Le Dinh Khiet , Pham Tien Lam , Dam Hieu Chi

Running quantum algorithms on real hardware is essential for understanding their strengths and limitations, especially in the noisy intermediate scale quantum (NISQ) era. Herein we focus on the practical aspect of quantum computational…

Quantum Physics · Physics 2022-08-12 Kentaro Yamamoto , David Zsolt Manrique , Irfan Khan , Hideaki Sawada , David Muñoz Ramo

A general procedure for the optimization of atomic density-fitting basis functions is designed with the balance between accuracy and numerical stability in mind. Given one-electron wavefunctions and energies, weights are assigned to the…

Chemical Physics · Physics 2020-10-13 Dimitri N. Laikov

Precise calculations of core properties in heavy-atom systems which are described by the operators heavily concentrated in atomic cores, like to hyperfine structure and P,T-parity nonconservation effects, usually require accounting for…

Atomic Physics · Physics 2015-06-26 A. V. Titov , N. S. Mosyagin , A. N. Petrov , T. A. Isaev

Basis set convergence of correlation effects on molecular atomization energies beyond the CCSD (coupled cluster with singles and doubles) approximation has been studied near the one-particle basis set limit. Quasiperturbative connected…

Chemical Physics · Physics 2008-08-17 Amir Karton , Peter R. Taylor , Jan M. L. Martin

In this study, we develop and implement a specialized coupled-cluster (CC) approach tailored for accurately describing atoms and molecules in strong magnetic fields. Using the open-source Ghent Quantum Chemistry Package (\texttt{GQCP}) in…

Atomic Physics · Physics 2025-07-14 T. Zalialiutdinov , D. Solovyev

We present a novel theory and implementation for computing coupled electronic and quantal nuclear subsystems on a single potential energy surface, moving beyond the standard Born-Oppenheimer (BO) separation of nuclei and electrons. We…

Chemical Physics · Physics 2021-11-15 Ziyong Chen , Jun Yang

We illustrate the description of correlated subsystems by studying the simple two-body Hydrogen atom. We study the entanglement of the electron and proton coordinates in the exact analytical solution. This entanglement, which we quantify in…

Quantum Physics · Physics 2009-10-30 Paolo Tommasini , Eddy Timmermans , A. F. R. de Toledo Piza

We present a novel "linear combination of atomic orbitals"-type of approximation, enabling accurate electronic structure calculations for systems of up to 20 or more electronically coupled quantum dots. Using realistic single quantum dot…

Mesoscale and Nanoscale Physics · Physics 2021-03-10 Alexander Mittelstädt , Ludwig A. Th. Greif , Stefan T. Jagsch , Andrei Schliwa