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The effects of the correlations in the ground state of $^{16}$O on the octupole and dipole excitations are studied using the extended random phase approximation (ERPA) derived from the time-dependent density-matrix theory. It is found that…

Nuclear Theory · Physics 2015-06-15 Mitsuru Tohyama

We report an improved implementation for evaluating the analytical gradients of the random phase approximation (RPA) electron-correlation energy based on atomic orbitals and the localized resolution of identity scheme. The more efficient…

Materials Science · Physics 2024-04-17 Muhammad N. Tahir , Honghui Shang , Jia Li , Xinguo Ren

Concerning the su(2)-Lipkin model, the calculation of the excitation energy to the 1st excited-state gives rise to the following fact: The two results based on the exact treatment and the conventional random phase approximation (RPA) are in…

Nuclear Theory · Physics 2022-07-27 Y. Tsue , C. Providencia , J. da Providencia , M. Yamamura

We make use of a subtraction procedure, introduced to overcome double--counting problems in beyond--mean--field theories, in the second random--phase--approximation (SRPA) for the first time. This procedure guarantees the stability of SRPA…

Nuclear Theory · Physics 2015-09-09 D. Gambacurta , M. Grasso , J. Engel

We present a quantum algorithm for the simulation of molecular systems that is asymptotically more efficient than all previous algorithms in the literature in terms of the main problem parameters. As in previous work [Babbush et al., New…

We formulate a microscopic theory to calculate cross section of the radiative neutron capture reaction on neutron-rich nuclei using the continuum random-phase approximation (cRPA) to the time-dependent density functional theory (TDDFT).…

Nuclear Theory · Physics 2023-06-28 Teruyuki Saito , Masayuki Matsuo

We use a spin-rotational invariant Gutzwiller energy functional to compute random-phase-approximation-like (RPA) fluctuations on top of the Gutzwiller approximation (GA). The method can be viewed as an extension of the previously developed…

Strongly Correlated Electrons · Physics 2008-06-16 G. Seibold , F. Becca , P. Rubin , J. Lorenzana

Phase separation of the ultrasoft restricted primitive model (URPM) with Gaussian charges is re-investigated in the random phase approximation (RPA)---the 'Level A' approximation discussed by Nikoubashman, Hansen and Kahl [J. Chem. Phys.…

Statistical Mechanics · Physics 2013-02-22 Patrick B. Warren , Andrew J. Masters

Quantum amplitude estimation is one of the core subroutines in quantum algorithms. This paper gives a parallelized amplitude estimation (PAE) algorithm that simultaneously achieves near-Heisenberg scaling in the total number of queries and…

Quantum Physics · Physics 2026-04-10 Kohei Oshio , Kaito Wada , Naoki Yamamoto

Several approaches to photonuclear reactions, based on the time-dependent density-functional theory, have been developed recently. The standard linearization leads to the random-phase approximation (RPA) or the quasiparticle-random-phase…

We propose the regularized compressed double factorization (RC-DF) method to classically compute compressed representations of molecular Hamiltonians that enable efficient simulation with noisy intermediate scale (NISQ) and error corrected…

In this work, a scalable algorithm for the approximate quantum state preparation problem is proposed, facing a challenge of fundamental importance in many topic areas of quantum computing. The algorithm uses a variational quantum circuit…

Quantum Physics · Physics 2025-03-19 Giacomo Belli , Marco Mordacci , Michele Amoretti

We explore different variants of the random phase approximation (RPA) to the correlation energy derived from closed-shell ring-diagram approximations to coupled cluster doubles theory. We implement these variants in range-separated…

Chemical Physics · Physics 2011-09-01 Julien Toulouse , Wuming Zhu , Andreas Savin , Georg Jansen , János G. Angyán

The self-consistent random phase approximation (RPA) based on a correlated realistic nucleon-nucleon interaction is used to evaluate correlation energies in closed-shell nuclei beyond the Hartree-Fock level. The relevance of contributions…

Nuclear Theory · Physics 2007-05-23 C. Barbieri , N. Paar , R. Roth , P. Papakonstantinou

Quantum algorithms for linear systems produce the solution state $A^{-1}|b\rangle$ by querying two oracles: $O_A$ that block encodes the coefficient matrix and $O_b$ that prepares the initial state. We present a quantum linear system…

Quantum Physics · Physics 2026-03-24 Guang Hao Low , Yuan Su

We present new algorithms for estimating and testing \emph{collision probability}, a fundamental measure of the spread of a discrete distribution that is widely used in many scientific fields. We describe an algorithm that satisfies…

Machine Learning · Statistics 2025-04-21 Robert Busa-Fekete , Umar Syed

We present a quantum algorithm for solving algebraic Riccati equations, with applications to quantum-chemical random-phase approximation (RPA) and higher-order RPA theories. Our method block-encodes stabilizing Riccati solutions via Riesz…

Quantum Physics · Physics 2026-05-18 Pablo Rodenas-Ruiz , Andrew Zhao , Joonho Lee

We propose a fast method for high order approximation of potentials of the Helmholtz type operator Delta+kappa^2 over hyper-rectangles in R^n. By using the basis functions introduced in the theory of approximate approximations, the cubature…

Numerical Analysis · Mathematics 2019-10-29 Flavia Lanzara , Vladimir Maz'ya , Gunther Schmidt

The relativistic quasiparticle time-blocking approximation (RQTBA) is applied to the description of nuclear excitation modes of astrophysical interest. This method is based on the meson-nucleon Lagrangian and goes beyond the standard…

Nuclear Theory · Physics 2018-01-17 Caroline Robin , Elena Litvinova

The collective excitation phenomena in atomic nuclei are studied in two different formulations of the Random Phase Approximation (RPA): (i) RPA based on correlated realistic nucleon-nucleon interactions constructed within the Unitary…

Nuclear Theory · Physics 2009-11-11 N. Paar , P. Papakonstantinou , H. Hergert , R. Roth