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The fundamental problem faced in quantum chemistry is the calculation of molecular properties, which are of practical importance in fields ranging from materials science to biochemistry. Within chemical precision, the total energy of a…

The variational quantum eigensolver (VQE) algorithm combines the ability of quantum computers to efficiently compute expectation values with a classical optimization routine in order to approximate ground state energies of quantum systems.…

We solve a radial Schr\"odinger equation for the case of a multichannel square well plus an exponential potential in one of the channels. The solution is obtained by summing exactly the infinite terms of the perturbative series for the…

High Energy Physics - Phenomenology · Physics 2016-08-25 V. Antonelli , E. Torrente Lujan

Quantum computing has emerged as a promising platform for simulating strongly correlated systems in chemistry, for which the standard quantum chemistry methods are either qualitatively inaccurate or too expensive. However, due to the…

Chemical Physics · Physics 2024-05-06 Max Rossmannek , Fabijan Pavošević , Angel Rubio , Ivano Tavernelli

Computing accurate yet efficient approximations to the solutions of the electronic Schr\"odinger equation has been a paramount challenge of computational chemistry for decades. Quantum Monte Carlo methods are a promising avenue of…

Chemical Physics · Physics 2023-09-25 Zeno Schätzle , Bernát Szabó , Matĕj Mezera , Jan Hermann , Frank Noé

We present a fast direct solver for two dimensional scattering problems, where an incident wave impinges on a penetrable medium with compact support. We represent the scattered field using a volume potential whose kernel is the outgoing…

Numerical Analysis · Mathematics 2015-05-28 Sivaram Ambikasaran , Carlos Borges , Lise-Marie Imbert-Gerard , Leslie Greengard

In quantum mechanics textbooks, a single-particle scattering theory is introduced. In the present work, a generalized scattering theory is presented, which can be in principle applied to the scattering problems of arbitrary number of…

Quantum Physics · Physics 2023-07-06 Huai-Yu Wang

Years ago S. Weinberg suggested the "Quasi-Particle" method (Q-P) for iteratively solving an integral equation, based on an expansion in terms of sturmian functions that are eigenfunctions of the integral kernel. An improvement of this…

Computational Physics · Physics 2015-05-27 George Rawitscher

Boundary integral methods are advantageous when simulating viscous flow around rigid particles, due to the reduction in number of unknowns and straightforward handling of the geometry. In this work we present a fast and accurate framework…

Numerical Analysis · Mathematics 2016-09-22 Ludvig af Klinteberg , Anna-Karin Tornberg

The two-body Coulomb scattering problem is solved using the standard complex scaling method. The explicit enforcement of the scattering boundary condition is avoided. Splitting of the scattering wave function based on the Coulomb modified…

Atomic Physics · Physics 2015-06-03 I. Hornyak , A. T. Kruppa

Three different numerical techniques for solving a coupled channel Schroedinger equation are compared. This benchmark equation, which describes the collision between two ultracold atoms, consists of two channels, each containing the same…

Atomic Physics · Physics 2009-10-31 G. H. Rawitscher , B. D. Esry , E. Tiesinga , J. P. Burke

Coupled nonlinear Schr\"odinger equations model various physical phenomena, such as wave propagation in nonlinear optics, multi-component Bose-Einstein condensates, and shallow water waves. Despite their extensive applications, analytical…

Numerical Analysis · Mathematics 2024-07-29 Nate Lovett , Harish Bhatt

We present a novel multi-scale embedding scheme that links conventional QM/MM embedding and bootstrap embedding (BE) to allow simulations of large chemical systems on limited quantum devices. We also propose a mixed-basis BE scheme that…

Weinberg's theorem for \pi-\pi scattering, including the Adler zero at threshold in the chiral limit, is analytically proved for microscopic quark models that preserve chiral symmetry. Implementing Ward-Takahashi identities, the isospin 0…

High Energy Physics - Phenomenology · Physics 2008-11-26 Pedro Bicudo , Stephen Cotanch , Felipe Llanes-Estrada , Pieter Maris , Emilio Ribeiro , Adam Szczepaniak

Accurately describing strongly correlated electronic systems remains a central challenge in quantum chemistry, as electron-electron interactions give rise to complex many-body wavefunctions that are difficult to capture with conventional…

Real-world quantum systems interact with their environments, leading to the irreversible dynamics described by the Lindblad equation. Solutions to the Lindblad equation give rise to quantum channels $\Phi_t$ that characterize the evolution…

Quantum Physics · Physics 2025-03-07 L. Y. Visser , R. J. P. T. de Keijzer , O. Tse , S. J. J. M. F. Kokkelmans

A contracted quantum eigensolver (CQE) finds a solution to the many-electron Schr\"odinger equation by solving its integration (or contraction) to the 2-electron space -- a contracted Schr\"odinger equation (CSE) -- on a quantum computer.…

Quantum Physics · Physics 2022-05-05 Scott E. Smart , David A. Mazziotti

Currently, quantum scattering calculations cannot be used for quantitative predictions of molecular scattering observables at ultralow temperatures. This is a result of two problems: the extreme sensitivity of the scattering observables to…

Chemical Physics · Physics 2019-07-10 Masato Morita , Roman V. Krems , Timur V. Tscherbul

We present a new approach to real-space multiple-scattering theory for molecules and clusters, based on the two-potential (distorted-wave) Lippmann-Schwinger equation formalism. Our approach uses a recently developed form [D. L. Foulis,…

Mathematical Physics · Physics 2008-06-04 D. L. Foulis

We present a novel approach for the numerical solution of problems of elastic scattering by open arcs in two dimensions. Our methodology relies on the composition of weighted versions of the classical operators associated with Dirichlet and…

Numerical Analysis · Mathematics 2019-02-26 Oscar P. Bruno , Liwei Xu , Tao Yin