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We study the reliability of the constrained random phase approximation (cRPA) method for the calculation of low-energy effective Hamiltonians by considering multi-orbital lattice models with one strongly correlated "target" band and two…

Strongly Correlated Electrons · Physics 2015-07-24 Hiroshi Shinaoka , Matthias Troyer , Philipp Werner

Developing theoretical understanding of complex reactions and processes at interfaces requires using methods that go beyond semilocal density functional theory to accurately describe the interactions between solvent, reactants and…

The possibility of applying the Quasiparticle Tamm-Dancoff Approximation (QTDA) to describe the nuclear double beta decay is explored. Several serious inconveniences found in the Quasiparticle Random Phase Approximation (QRPA), such as: i)…

Nuclear Theory · Physics 2008-11-26 Franjo Krmpotić

Exact results of pair transfer probabilities for the Richardson model with equidistant or random level spacing are presented. The results are then compared either to particle-particle random phase approximation (ppRPA) in the normal phase…

Nuclear Theory · Physics 2015-06-11 Danilo Gambacurta , Denis Lacroix

Practical applications of fragment embedding and closely related local correlation methods critically depend on a judicious choice of a low-level theory to define the local embedding subspace and to capture long-range electrostatic and…

Chemical Physics · Physics 2026-05-14 Ruiheng Song , Xiliang Gong , Aamy Bakry , Hong-Zhou Ye

Calculations of the lowest valence {\pi}* as well as the 3s and higher energy 3p{\sigma} Rydberg excited states of the CO2 molecule are carried out using density functionals with variational optimization of the orbitals, an approach…

Chemical Physics · Physics 2026-04-08 Darío Barreiro-Lage , Gianluca Levi , Hannes Jonssón , Thanja Lamberts

We consider the rank-reduced coupled-cluster theory with single and double excitations (RR-CCSD) introduced recently [Parrish \emph{et al.}, J. Chem. Phys. {\bf 150}, 164118 (2019)]. The main feature of this method is the decomposed form of…

Chemical Physics · Physics 2022-02-21 Michał Lesiuk

This paper describes a method to do ab initio molecular dynamics in electronically excited systems within the random phase approximation (RPA). Using a dynamical variational treatment of the RPA frequency, which corresponds to the…

Condensed Matter · Physics 2009-10-31 Eric R. Bittner , D. S. Kosov

We present a quantum algorithm for simulating quantum chemistry with gate complexity $\tilde{O}(N^{1/3} \eta^{8/3})$ where $\eta$ is the number of electrons and $N$ is the number of plane wave orbitals. In comparison, the most efficient…

Quantum Physics · Physics 2019-11-06 Ryan Babbush , Dominic W. Berry , Jarrod R. McClean , Hartmut Neven

We propose a novel approach to electron correlation for multireference systems. It is based on particle-hole (ph) and particle-particle (pp) theories in the second-order, developed in the random phase approximation (RPA) framework for…

Chemical Physics · Physics 2024-12-03 Aleksandra Tucholska , Yang Guo , Katarzyna Pernal

Rydberg excited states of molecules pose a challenge for electronic structure calculations because of their highly diffuse electron distribution. Even large and elaborate atomic basis sets tend to underrepresent the long-range tail, overly…

We assess the performance of a recently proposed renormalized adiabatic local density approximation (rALDA) for \textit{ab initio} calculations of electronic correlation energies in solids and molecules. The method is an extension of the…

Materials Science · Physics 2014-05-30 Thomas Olsen , Kristian S. Thygesen

Pair atomic density fitting (PADF) is a promising strategy to reduce the scaling with system size of quantum chemical methods for the calculation of the correlation energy like the direct random phase approximation (RPA) or second-order…

Chemical Physics · Physics 2023-03-14 Edoardo Spadetto , Pier Herman Theodoor Philipsen , Arno Förster , Lucas Visscher

The RPA long range correlations are known to play a significant role in understanding the depletion of single particle-hole states observed in (e, e') and (e, e'p) measurements. Here the Random Phase Approximation (RPA) theory, implemented…

Nuclear Theory · Physics 2009-11-11 M. Dupuis , S. Karataglidis , E. Bauge , J. P. Delaroche , D. Gogny

The random phase approximation (RPA) for the electron correlation energy, combined with the exact-exchange energy, represents the state-of-the-art exchange-correlation functional within density-functional theory (DFT). However, the standard…

Other Condensed Matter · Physics 2015-05-20 Xinguo Ren , Patrick Rinke , Alexandre Tkatchenko , Matthias Scheffler

We present a quantum algorithm to solve systems of linear equations of the form $A\mathbf{x}=\mathbf{b}$, where $A$ is a tridiagonal Toeplitz matrix and $\mathbf{b}$ results from discretizing an analytic function, with a circuit complexity…

Quantum Physics · Physics 2022-01-17 Almudena Carrera Vazquez , Ralf Hiptmair , Stefan Woerner

It is shown that the random-phase approximation (RPA) method with its nonlinear generalization, which was previously considered as approximation, reproduces the exact solutions of the Lipkin model. The nonlinear RPA is based on an equation…

Nuclear Theory · Physics 2017-11-22 J. Terasaki , A. Smetana , F. Šimkovic , M. I. Krivoruchenko

Density functional theory is a preferred microscopic method for calculation of nuclear properties over the whole nuclear chart. Besides ground-state properties, which are calculated by Hartree-Fock theory, nuclear excitations can be…

Nuclear Theory · Physics 2020-06-02 Anton Repko

In this work, we derive particle schemes, based on micro-macro decomposition, for linear kinetic equations in the diffusion limit. Due to the particle approximation of the micro part, a splitting between the transport and the collision part…

Numerical Analysis · Mathematics 2017-01-19 Anaïs Crestetto , Nicolas Crouseilles , Mohammed Lemou

We develop and implement a formalism which enables calculating the analytical gradients of particle-hole random-phase approximation (RPA) ground-state energy with respect to the atomic positions within the atomic orbital basis set…

Chemical Physics · Physics 2021-09-03 Muhammad N. Tahir , Tong Zhu , Honghui Shang , Jia Li , Volker Blum , Xinguo Ren