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Harnessing the full power of nascent quantum processors requires the efficient management of a limited number of quantum bits with finite lifetime. Hybrid algorithms leveraging classical resources have demonstrated promising initial results…

This paper explores variants of the subspace iteration algorithm for computing approximate invariant subspaces. The standard subspace iteration approach is revisited and new variants that exploit gradient-type techniques combined with a…

Numerical Analysis · Mathematics 2024-05-14 Foivos Alimisis , Yousef Saad , Bart Vandereycken

We consider the problem of attaining either the maximal increase or reduction of the robustness of a complex network by means of a bounded modification of a subset of the edge weights. We propose two novel strategies combining Krylov…

Numerical Analysis · Mathematics 2023-09-21 Stefano Massei , Francesco Tudisco

The generalized pseudospectral method is employed to study the bound-state spectra of some of the exponentially screened Coulomb potentials, \emph{viz.}, the exponential cosine screened Coulomb (ECSC) and general exponential screened…

Quantum Physics · Physics 2013-04-26 Amlan K. Roy

The generalized pseudospectral method is employed to calculate the bound states of Hulth\'en and Yukawa potentials in quantum mechanics, with special emphases on higher excited states and stronger couplings. Accurate energy eigenvalues,…

Quantum Physics · Physics 2015-06-18 Amlan K. Roy

Chebyshev filter diagonalization is well established in quantum chemistry and quantum physics to compute bulks of eigenvalues of large sparse matrices. Choosing a block vector implementation, we investigate optimization opportunities on the…

Mathematical Software · Computer Science 2020-06-25 Moritz Kreutzer , Georg Hager , Dominik Ernst , Holger Fehske , Alan R. Bishop , Gerhard Wellein

In this paper, we apply a specifically designed dissipative spatial filter as sub-grid scale model within the increasingly popular discontinuous Galerkin methods and the closely related flux reconstruction high order methods for large eddy…

Computational Engineering, Finance, and Science · Computer Science 2020-02-19 David G Flad , Andrea D Beck , Philipp Guthke

We report quantum chemistry calculations performed on superconducting quantum processors for a molecule exhibiting the half-M\"obius electronic topology originally introduced by Ron\v{c}evi\'c et al. Using SqDRIFT, a randomized sample-based…

Efficient and stable algorithms for the calculation of spectral quantities and correlation functions are some of the key tools in computational condensed matter physics. In this article we review basic properties and recent developments of…

Other Condensed Matter · Physics 2007-05-23 Alexander Weisse , Gerhard Wellein , Andreas Alvermann , Holger Fehske

Pipelined Krylov subspace methods avoid communication latency by reducing the number of global synchronization bottlenecks and by hiding global communication behind useful computational work. In exact arithmetic pipelined Krylov subspace…

Numerical Analysis · Computer Science 2019-03-26 Siegfried Cools

Optimal phase estimation protocols require complex state preparation and readout schemes, generally unavailable or unscalable in many quantum platforms. We develop and analyze a scheme that achieves near-optimal precision up to a constant…

Quantum Physics · Physics 2026-02-16 Su Direkci , Ran Finkelstein , Manuel Endres , Tuvia Gefen

It is needed to solve generalized eigenvalue problems (GEP) in many applications, such as the numerical simulation of vibration analysis, quantum mechanics, electronic structure, etc. The subspace iteration is a kind of widely used…

Numerical Analysis · Mathematics 2023-01-02 Biyi Wang , Hengbin An , Hehu Xie , Zeyao Mo

We revisit the collocation method of Manzhos and Carrington (J. Chem. Phys. 145, 224110, 2016) in which a distributed localized (e.g., Gaussian) basis is used to set up a generalized eigenvalue problem to compute the eigenenergies and…

Chemical Physics · Physics 2021-08-30 Shane W. Flynn , Vladimir A. Mandelshtam

We consider the problem of parallelizing electronic structure computations in plane-wave Density Functional Theory. Because of the limited scalability of Fourier transforms, parallelism has to be found at the eigensolver level. We show how…

Computational Physics · Physics 2015-06-22 Antoine Levitt , Marc Torrent

Variational Quantum Eigensolvers (VQEs) represent a promising approach to computing molecular ground states and energies on modern quantum computers. These approaches use a classical computer to optimize the parameters of a trial wave…

The GW approximation for the electronic self-energy is an important tool for the quantitative prediction of excited states in solids, but its mathematical exploration is hampered by the fact that it must, in general, be evaluated…

Materials Science · Physics 2013-02-27 Arno Schindlmayr

In this work we investigate in detail, the different regimes of the pioneering work of Chklovskii et al. (1992), which provides an analytical description to model the electrostatics at the edges of a two-dimensional electron gas. We take…

Mesoscale and Nanoscale Physics · Physics 2015-06-11 A. Salman , M. B. Yucel , A. Siddiki

A direct orbital optimization method is presented for density functional calculations of excited electronic states using either a real space grid or a plane wave basis set. The method is variational, provides atomic forces in the excited…

Computational Physics · Physics 2022-11-09 Aleksei V. Ivanov , Gianluca Levi , Elvar Ö. Jónsson , Hannes Jónsson

The $GW$ approximation has recently gained increasing attention as a viable method for the computation of deep core-level binding energies as measured by X-ray photoelectron spectroscopy (XPS). We present a comprehensive benchmark study of…

Chemical Physics · Physics 2022-06-14 Jiachen Li , Ye Jin , Patrick Rinke , Weitao Yang , Dorothea Golze

We provide a detailed estimate for the logical resource requirements of the quantum linear system algorithm (QLSA) [Phys. Rev. Lett. 103, 150502 (2009)] including the recently described elaborations [Phys. Rev. Lett. 110, 250504 (2013)].…