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A variational method for computing conformational properties of molecules with Lennard-Jones potentials for the monomer-monomer interactions is presented. The approach is tailored to deal with angular degrees of freedom, {\it rotors}, and…

chem-ph · Physics 2016-08-31 Carsten Peterson , Ola Sommelius , Bo Söderberg

The development of computational resources has made it possible to determine upper bounds for atomic and molecular energies with high precision. Yet, error bounds to the computed energies have been available only as estimates. In this…

Chemical Physics · Physics 2023-01-10 Miklos Ronto , Peter Jeszenszki , Edit Mátyus , Eli Pollak

We analyse a two-particle quantum system in $\R^d$ with interaction and in presence of a random external potential field with a continuous argument (an Anderson model in a continuous space). Our aim is to establish the so-called Wegner-type…

Mathematical Physics · Physics 2008-12-16 A. Boutet de Monvel , V. Chulaevsky , Y. Suhov

For classical lattice systems, the Dobrushin-Lanford-Ruelle theory of boundary conditions states that the restriction of a global equilibrium state to a subsystem can be obtained as an integral over equilibrium states of the subsystem…

Condensed Matter · Physics 2007-05-23 M. Fannes , R. F. Werner

We use the worldline representation of field theory together with a variational approximation to determine the lowest bound state in the scalar Wick-Cutkosky model where two equal-mass constituents interact via the exchange of mesons.…

High Energy Physics - Phenomenology · Physics 2009-11-11 K. Barro-Bergflödt , R. Rosenfelder , M. Stingl

Solving non-Hermitian quantum many-body systems on a quantum computer by minimizing the variational energy is challenging as the energy can be complex. Here, based on energy variance, we propose a variational method for solving the…

Quantum Physics · Physics 2024-02-21 Xu-Dan Xie , Zheng-Yuan Xue , Dan-Bo Zhang

Consider a linear autonomous Hamiltonian system with a time periodic bound state solution. In this paper we study the structural instability of this bound state ^M relative to time almost periodic perturbations which are small, localized…

Pattern Formation and Solitons · Physics 2009-09-25 Eduard Kirr , Michael I. Weinstein

Solving optimisation problems encoded in the ground state of classical-spin systems is a focus area for quantum computing devices, providing upper bounds to the unknown solution. To certify these bounds, they are compared to those obtained…

Quantum Physics · Physics 2020-11-04 Flavio Baccari , Christian Gogolin , Peter Wittek , Antonio Acín

We assess two different non-equilibrium quantum Landauer bounds: the traditional approach based on the change in entropy, referred to as the `entropic bound', and one based on the details of the dynamical map, referred to as the…

Quantum Physics · Physics 2017-10-16 Steve Campbell , Giacomo Guarnieri , Mauro Paternostro , Bassano Vacchini

We consider the spectral and dynamical properties of quantum systems of $n$ particles on the lattice $\Z^d$, of arbitrary dimension, with a Hamiltonian which in addition to the kinetic term includes a random potential with iid values at the…

Mathematical Physics · Physics 2015-05-13 Michael Aizenman , Simone Warzel

Estimating ground state energies of many-body Hamiltonians is a central task in many areas of quantum physics. In this work, we give quantum algorithms which, given any $k$-body Hamiltonian $H$, compute an estimate for the ground state…

Semidefinite relaxations of polynomial optimization have become a central tool for addressing the non-convex optimization problems over non-commutative operators that are ubiquitous in quantum information theory and, more in general,…

Quantum Physics · Physics 2025-12-22 Younes Naceur , Jie Wang , Victor Magron , Antonio Acín

Analog models of quantum information processing, such as adiabatic quantum computation and analog quantum simulation, require the ability to subject a system to precisely specified Hamiltonians. Unfortunately, the hardware used to implement…

Quantum Physics · Physics 2014-02-25 Kevin C. Young , Robin Blume-Kohout , Daniel A. Lidar

A numerical procedure providing guaranteed two-sided bounds on the effective coefficients of elliptic partial differential operators is presented. The upper bounds are obtained in a standard manner through the variational formulation of the…

Numerical Analysis · Mathematics 2023-07-24 Liya Gaynutdinova , Martin Ladecký , Aleš Nekvinda , Ivana Pultarová , Jan Zeman

Solutions to many important partial differential equations satisfy bounds constraints, but approximations computed by finite element or finite difference methods typically fail to respect the same conditions. Chang and Nakshatrala enforce…

Numerical Analysis · Mathematics 2024-03-14 Robert C. Kirby , Daniel Shapero

A one-step analysis of Anderson acceleration with general algorithmic depths is presented. The resulting residual bounds within both contractive and noncontractive settings reveal the balance between the contributions from the higher and…

Numerical Analysis · Mathematics 2022-09-08 Sara Pollock , Leo Rebholz

A fertile area of recent research has demonstrated concrete polynomial time lower bounds for solving natural hard problems on restricted computational models. Among these problems are Satisfiability, Vertex Cover, Hamilton Path, Mod6-SAT,…

Computational Complexity · Computer Science 2010-02-03 Ryan Williams

This paper demonstrates the application of semidefinite programming to lattice field theories, showcasing spin chains and lattice scalar field theory. Requiring expectation values of manifestly positive semi-definite operators to be…

High Energy Physics - Lattice · Physics 2021-11-29 Scott Lawrence

Determining quantum excited states is crucial across physics and chemistry but presents significant challenges for variational methods, primarily due to the need to enforce orthogonality to lower-energy states, often requiring…

Quantum Physics · Physics 2025-05-01 Shi-Xin Zhang , Lei Wang

In our recent work \cite{StojnicHopBnds10} we looked at a class of random optimization problems that arise in the forms typically known as Hopfield models. We viewed two scenarios which we termed as the positive Hopfield form and the…

Optimization and Control · Mathematics 2013-06-19 Mihailo Stojnic