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We apply a variational method devised for the nuclear many--body problem to the 1-dimensional Hubbard--model with nearest neighbor hopping and periodic boundary conditions. The test wave function consist for each state out of a single…

Strongly Correlated Electrons · Physics 2008-11-26 K. W. Schmid , T. Dahm , J. Margueron , H. Müther

The variational perturbation theory for wave functions, which has been shown to work well for bound states of the anharmonic oscillator, is applied to resonance states of the anharmonic oscillator with negative coupling constant. We obtain…

High Energy Physics - Theory · Physics 2009-10-30 T. Tanaka

Eigenstate preparation is ubiquitous in quantum computing, and a standard approach for generating the lowest-energy states of a given system is by employing adiabatic state preparation (ASP). In the present work, we investigate a…

Quantum Physics · Physics 2021-08-30 Shunji Matsuura , Samantha Buck , Valentin Senicourt , Arman Zaribafiyan

We show that quasiparticle (QP) energies as calculated in the $GW$ approximation converge to the wrong value using the projector augmented wave (PAW) method, since the overlap integrals between occupied orbitals and high energy, plane wave…

Materials Science · Physics 2014-08-20 Jiří Klimeš , Merzuk Kaltak , Georg Kresse

Variational wave function ansatze are an invaluable tool to study the properties of strongly correlated systems. We propose such a wave function, based on the theory of auxiliary fields and combining aspects of auxiliary-field quantum Monte…

Strongly Correlated Electrons · Physics 2024-03-13 Ryan Levy , Miguel A. Morales , Shiwei Zhang

Variable projection solves structured optimization problems by completely minimizing over a subset of the variables while iterating over the remaining variables. Over the last 30 years, the technique has been widely used, with empirical and…

Optimization and Control · Mathematics 2020-11-23 Tristan van Leeuwen , Aleksandr Aravkin

The performance of basis sets made of numerical atomic orbitals is explored in density-functional calculations of solids and molecules. With the aim of optimizing basis quality while maintaining strict localization of the orbitals, as…

Materials Science · Physics 2009-11-07 Javier Junquera , Oscar Paz , Daniel Sanchez-Portal , Emilio Artacho

The matching of multiple objects (e.g. shapes or images) is a fundamental problem in vision and graphics. In order to robustly handle ambiguities, noise and repetitive patterns in challenging real-world settings, it is essential to take…

Computer Vision and Pattern Recognition · Computer Science 2019-03-15 Florian Bernard , Johan Thunberg , Paul Swoboda , Christian Theobalt

Many inverse problems involve two or more sets of variables that represent different physical quantities but are tightly coupled with each other. For example, image super-resolution requires joint estimation of the image and motion…

Numerical Analysis · Mathematics 2019-06-26 James Herring , James Nagy , Lars Ruthotto

We develop a new approach to robust adaptive beamforming in the presence of signal steering vector errors. Since the signal steering vector is known imprecisely, its presumed (prior) value is used to find a more accurate estimate of the…

Information Theory · Computer Science 2012-05-15 Arash Khabbazibasmenj , Sergiy A. Vorobyov , Aboulnasr Hassanien

It is pointed out that the "counter example" presented in the Comment is a family of probe wave functions which are increasingly broad as the shift becomes large. Furthermore, the author's variational calculation is not correct in the sense…

Quantum Physics · Physics 2013-04-16 Yuki Susa , Yutaka Shikano , Akio Hosoya

Nonlinear Convex Cone Programming (NCCP) problems are important and have many practical applications. In this paper, we introduces a flexible first-order primal-dual algorithm called the Variant Auxiliary Problem Principle (VAPP) for…

Optimization and Control · Mathematics 2019-11-05 Lei Zhao , Daoli Zhu

In a recent work, van Setten and coworkers have presented a carefully converged $G_0W_0$ study of 100 closed shell molecules [J. Chem. Theory Comput. 11, 5665 (2015)]. For two different codes they found excellent agreement to within few 10…

Materials Science · Physics 2016-11-28 Emanuele Maggio , Peitao Liu , Michiel J. van Setten , Georg Kresse

The norms or expectation values of infinite projected entangled-pair states (PEPS) cannot be computed exactly, and approximation algorithms have to be applied. In the last years, many efficient algorithms have been devised -- the corner…

We develop a canonical framework for the study of the problem of registration of multiple point processes subjected to warping, known as the problem of separation of amplitude and phase variation. The amplitude variation of a real random…

Statistics Theory · Mathematics 2016-03-30 Victor M. Panaretos , Yoav Zemel

Approximate Message Passing (AMP), originally designed to solve high-dimensional linear inverse problems, has found broad applications in signal processing and statistical inference. Among its key variants, Vector Approximate Message…

Information Theory · Computer Science 2024-10-29 Qun Chen , Haochuan Zhang , Huimin Zhu

The purpose of this text is to give a self-contained description of the basic theory of the projector augmented-wave (PAW) method, as well as most of the details required to make the method work in practice. These two topics are covered in…

Materials Science · Physics 2009-10-13 Carsten Rostgaard

High accuracy calculations of atomic properties require using long basis sets. In particular, it is necessary to include large number of partial waves and estimate truncation corrections. The convergence in partial waves is known to be…

Atomic Physics · Physics 2026-03-27 M. G. Kozlov

We present an analytical method for the two-qubit quantum Rabi model. While still operating in the frame of the generalized rotating-wave approximation (GRWA), our method further embraces the idea of introducing variational parameters. The…

Quantum Physics · Physics 2019-04-23 Bin-Bin Mao , Liangsheng Li , Yimin Wang , Wen-Long You , Wei Wu , Maoxin Liu , Hong-Gang Luo

We explore the possibility of using "weak" measurements to carry out quantum state tomography. Given a certain fixed number of copies of identically prepared states of a qubit, we simulate state tomography using weak as well as projective…

Quantum Physics · Physics 2014-08-06 Debmalya Das , Arvind