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Large scale Density Functional Theory (DFT) based electronic structure calculations are highly time consuming and scale poorly with system size. While semi-empirical approximations to DFT result in a reduction in computational time versus…

Materials Science · Physics 2016-12-21 Ganesh Hegde , R. Chris Bowen

A theoretical approach was developed for an exact numerical description of a pair of ultracold atoms interacting via a central potential that are trapped in a three-dimensional optical lattice. The coupling of center-of-mass and…

Quantum Physics · Physics 2013-05-29 Sergey Grishkevich , Alejandro Saenz

The performance of computational methods for many-body physics and chemistry is strongly dependent on the choice of basis used to cast the problem; hence, the search for better bases and similarity transformations is important for progress…

The ambiguity involved in the definition of effective-mass Hamiltonians for nonrelativistic models is resolved using the Dirac equation. The multistep approximation is extended for relativistic cases allowing the treatment of arbitrary…

Condensed Matter · Physics 2009-10-31 R. Renan , M. H. Pacheco , C. A. S. Almeida

We consider the efficient solution of strongly elliptic partial differential equations with random load based on the finite element method. The solution's two-point correlation can efficiently be approximated by means of an…

Numerical Analysis · Mathematics 2017-03-21 Jürgen Dölz , Helmut Harbrecht , Michael D. Peters

A framework to systematically decouple high order elliptic equations into combination of Poisson-type and Stokes-type equations is developed. The key is to systematically construct the underling commutative diagrams involving the complexes…

Numerical Analysis · Mathematics 2018-07-03 Long Chen , Xuehai Huang

Doping compounds can be considered a perturbation to the nuclear charges in a molecular Hamiltonian. Expansions of this perturbation in a Taylor series, i.e. quantum alchemy, has been used in literature to assess millions of derivative…

Chemical Physics · Physics 2024-06-19 Guido Falk von Rudorff

We present a four-component relativistic unitary coupled cluster method for molecules. We have used commutator-based non-perturbative approximation using the ''Bernoulli expansion'' to derive an approximation to the relativistic unitary…

Chemical Physics · Physics 2024-03-06 Kamal Majee , Tamoghna Mukhopadhyay , Malaya K. Nayak , Achintya Kumar Dutta

We show how to derive fixed-point Hamiltonians in quantum mechanics from a proposed renormalization group invariance approach that relies in a subtraction procedure at a given energy scale. The scheme is valid for arbitrary interactions…

High Energy Physics - Phenomenology · Physics 2007-05-23 T. Frederico , A. Delfino , Lauro Tomio , V. S. Timoteo

We present a quantum algorithm to obtain the response of the atomic nucleus to a small external electromagnetic perturbation. The Hamiltonian of the system is presented by a harmonic oscillator, and the linear combination of unitaries (LCU)…

Quantum Physics · Physics 2022-10-18 Abhishek , Nifeeya Singh , Pooja Siwach , P. Arumugam

There are three essential problems in computational relativistic chemistry: electrons moving at relativistic speeds, close lying states and dynamical correlation. Currently available quantum-chemical methods are capable of solving systems…

Chemical Physics · Physics 2020-05-08 Jan Brandejs , Jakub Višňák , Libor Veis , Maté Mihály , Örs Legeza , Jiří Pittner

Last years witnessed a remarkable interest in application of quantum computing for solving problems in quantum chemistry more efficiently than classical computers allow. Very recently, even first proof-of-principle experimental realizations…

Quantum Physics · Physics 2013-05-30 Libor Veis , Jakub Višňák , Timo Fleig , Stefan Knecht , Trond Saue , Lucas Visscher , Jiří Pittner

Localized basis sets in the projector augmented wave formalism allow for computationally efficient calculations within density functional theory (DFT). However, achieving high numerical accuracy requires an extensive basis set, which also…

Materials Science · Physics 2020-11-18 G. Gandus , A. Valli , D. Passerone , R. Stadler

In parallel to the unified construction of relativistic Hamiltonians based solely on physical arguments [J. Chem. Phys. 160, 084111 (2024)], a unified implementation of relativistic wave function methods is achieved here via programming…

Chemical Physics · Physics 2024-07-26 Ning Zhang , Wenjian Liu

We consider a single particle tunnelling in a tight-binding model with nearest-neighbour couplings, in the presence of a periodic high-frequency force. An effective Hamiltonian for the particle is derived using an averaging method…

Other Condensed Matter · Physics 2014-02-07 A. P. Itin , A. I. Neishtadt

We present the theory and implementation of a highly efficient relativistic third-order algebraic diagrammatic construction [ADC(3)] method based on a four-component (4c) Dirac-Coulomb (DC) Hamiltonian for the calculation of ionization…

Chemical Physics · Physics 2024-11-01 Sudipta Chakraborty , Tamoghna Mukhopadhyay , Malaya K. Nayak , Achintya Kumar Dutta

An adaptation of the full configuration interaction quantum Monte Carlo (FCIQMC) method is presented, for correlated electron problems containing heavy elements and the presence of significant relativistic effects. The modified algorithm…

Chemical Physics · Physics 2020-10-26 Robert J. Anderson , George H. Booth

We lay out the extension of range-separated density-functional theory to a four-component relativistic frame-work using a Dirac-Coulomb-Breit Hamiltonian in the no-pair approximation. This formalism combines a wave-function method for the…

Chemical Physics · Physics 2018-12-12 Julien Paquier , Julien Toulouse

Variational algorithms for strongly correlated chemical and materials systems are one of the most promising applications of near-term quantum computers. We present an extension to the variational quantum eigensolver that approximates the…

Quantum Physics · Physics 2020-08-26 William J. Huggins , Joonho Lee , Unpil Baek , Bryan O'Gorman , K. Birgitta Whaley

The Hamiltonian eigenvalue problem for bound states of a quantum field theory is formulated in terms of Dirac's light-front coordinates and then approximated by the exponential-operator technique of the standard coupled-cluster method. This…

High Energy Physics - Phenomenology · Physics 2012-06-27 J. R. Hiller