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In the case of the one-electron Dirac equation with a point nucleus the Virial Theorem (VT) states that the ratio of the kinetic energy to potential energy is exactly $-1$, a ratio that can be an independent test of the accuracy of a…

Atomic Physics · Physics 2021-09-28 Charlotte Froese Fischer , Michel Godefroid

The Configuration Interaction (CI) method using a large Laguerre basis restricted to l = 0 orbitals is applied to the calculation of the He ground state. The maximum number of orbitals included was 60. The numerical evidence suggests that…

Atomic Physics · Physics 2007-05-23 J. Mitroy , M. W. J. Bromley , K. Ratnavelu

A functional $E_{xc}[\rho(\r,\epsilon)]$ is presented, in which the exchange and correlation energy of an electron gas depends on the local density of occupied states. A simple local parametrization scheme is proposed, entirely from first…

Materials Science · Physics 2009-11-10 Jose M. Soler

Energy-based models are a simple yet powerful class of probabilistic models, but their widespread adoption has been limited by the computational burden of training them. We propose a novel loss function called Energy Discrepancy (ED) which…

Machine Learning · Statistics 2023-11-28 Tobias Schröder , Zijing Ou , Jen Ning Lim , Yingzhen Li , Sebastian J. Vollmer , Andrew B. Duncan

The calculation of excited state energies of electronic structure Hamiltonians has many important applications, such as the calculation of optical spectra and reaction rates. While low-depth quantum algorithms, such as the variational…

Quantum Physics · Physics 2019-07-03 Oscar Higgott , Daochen Wang , Stephen Brierley

We review the Lorentz integral transform coupled-cluster method for the calculation of the electric dipole polarizability. We benchmark our results with exact hyperspherical harmonics calculations for 4He and then we move to a heavier…

We investigate asymmetric nuclear matter with two- and three-nucleon interactions based on chiral effective field theory, where three-body forces are fit only to light nuclei. Focusing on neutron-rich matter, we calculate the energy for…

Nuclear Theory · Physics 2015-06-17 C. Drischler , V. Soma , A. Schwenk

We report a variational approach to the nonlinearly screened interaction of charged particles with a many-electron system. This approach has been developed by introducing a modification of the Schwinger variational principle of scattering…

Materials Science · Physics 2009-11-11 V. U. Nazarov , S. Nishigaki , J. M. Pitarke , C. S. Kim

This paper presents a fortran program to solve diverse few-body problems with the stochastic variational method. Depending on the available computational resources the program is applicable for $N=2-3-4-5-6-...$-body systems with $L=0$…

Nuclear Theory · Physics 2009-10-30 K. Varga , Y. Suzuki

We define the concept of energy-variational solutions for the Ericksen--Leslie equations in three spatial dimensions. This solution concept is finer than dissipative solutions and satisfies the weak-strong uniqueness property. For a certain…

Numerical Analysis · Mathematics 2023-12-22 Robert Lasarzik , Maximilian E. V. Reiter

The rich phenomenology of quantum many-body systems such as atomic nuclei is complex to interpret. Often, the behaviour (e.g. evolution with the number of constituents) of measurable/observable quantities such as binding or excitation…

Nuclear Theory · Physics 2024-04-30 Vittorio Somà , Thomas Duguet

The neutron-matter equation of state constrains the properties of many physical systems over a wide density range and can be studied systematically using chiral effective field theory (EFT). In chiral EFT, all many-body forces among…

Nuclear Theory · Physics 2013-08-13 T. Krüger , I. Tews , K. Hebeler , A. Schwenk

The calculation of potential energy surfaces for quantum dynamics can be a time consuming task -- especially when a high level of theory for the electronic structure calculation is required. We propose an adaptive interpolation algorithm…

Chemical Physics · Physics 2016-08-24 Markus Kowalewski , Elisabeth Larsson , Alfa Heryudono

The problem is addressed of defining the values of functions, whose variables tend to infinity, from the knowledge of these functions at asymptotically small variables close to zero. For this purpose, the extrapolation by means of different…

Statistical Mechanics · Physics 2010-10-05 S. Gluzman , V. I. Yukalov

Quantum optimization algorithms offer a promising route to finding the ground states of target Hamiltonians on near-term quantum devices. None the less, it remains necessary to limit the evolution time and circuit depth as much as possible,…

Quantum Physics · Physics 2022-11-01 Chenfeng Cao , Yunlong Yu , Zipeng Wu , Nic Shannon , Bei Zeng , Robert Joynt

By judicious use of extrapolations to the 1-particle basis set limit and $n$-particle calibration techniques, total atomization energies of molecules with up to four heavy atoms can be obtained with calibration accuracy (1 kJ/mol or better,…

Chemical Physics · Physics 2007-05-23 Jan M. L. Martin

The analysis of correlation energy of the simplest first approximation of a variational method for the intrashell states of two-electron atoms is the purpose of the present work. This method allows to divide energy of atom on Coulomb and…

Atomic Physics · Physics 2008-10-23 V. V. Kavera

Selected configuration interaction (SCI) methods have emerged as state-of-the-art methodologies for achieving high accuracy and generating benchmark reference data for ground and excited states in small molecular systems. However, their…

Chemical Physics · Physics 2024-06-13 Hugh G. A. Burton , Pierre-François Loos

We calculate the energy per particle in infinite neutron matter perturbatively using chiral N3LO two-body potentials plus N2LO three-body forces. The cutoff dependence of the predictions is investigated by employing chiral interactions with…

Nuclear Theory · Physics 2015-06-11 L. Coraggio , J. W. Holt , N. Itaco , R. Machleidt , F. Sammarruca

The electron and photon transport processes in spectroscopy techniques described by the invariant embedding theory is here revisited. We report a convergence method to obtain closed analytical solutions to the 3D integro-differential…

Materials Science · Physics 2010-06-22 Carlos Figueroa , Horacio Brizuela , Silvia P. Heluani