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Point-ion models have been extensively used to determine "hole numbers" at copper and oxygen sites in high-temperature superconducting cuprate compounds from measured nuclear quadrupole frequencies. The present study assesses the…

Superconductivity · Physics 2016-08-31 E. P. Stoll , P. F. Meier , T. A. Claxton

In this study, we propose a quantum-classical hybrid scheme for performing orbital-free density functional theory (OFDFT) using probabilistic imaginary-time evolution (PITE), designed for the era of fault-tolerant quantum computers (FTQC),…

Quantum Physics · Physics 2024-07-24 Yusuke Nishiya , Hirofumi Nishi , Taichi Kosugi , Yu-ichiro Matsushita

In this work, we introduce a differentiable implementation of the local natural orbital coupled cluster (LNOCC) method within the automatic differentiation framework of the PySCFAD package. The implementation is comprehensively tuned for…

Chemical Physics · Physics 2024-07-08 Xing Zhang , Chenghan Li , Hong-Zhou Ye , Timothy C. Berkelbach , Garnet Kin-Lic Chan

Analytical gradients of the total energy are provided for local density and generalized-gradient hybrid approximations to generalized Kohn-Sham spin-current density functional theory (SCDFT). It is shown that gradients may be determined…

Materials Science · Physics 2023-07-21 Jacques K. Desmarais , Alessandro Erba , Jean-Pierre Flament

Approximate natural orbitals are investigated as a way to improve a Monte Carlo configuration interaction (MCCI) calculation. We introduce a way to approximate the natural orbitals in MCCI and test these and approximate natural orbitals…

Chemical Physics · Physics 2013-04-12 J. P. Coe , M. J. Paterson

The nuclear-electronic orbital (NEO) method is a well-established approach for treating nuclei quantum mechanically in molecular systems beyond the usual Born-Oppenheimer approximation. In this work, we present a strategy to implement the…

Computational Physics · Physics 2022-06-29 Jianhang Xu , Ruiyi Zhou , Zhen Tao , Christopher Malbon , Volker Blum , Sharon Hammes-Schiffer , Yosuke Kanai

We introduce an orbital free electron density functional approximation based on alchemical perturbation theory. Given convergent perturbations of a suitable reference system, the accuracy of popular self-consistent Kohn-Sham density…

Chemical Physics · Physics 2020-05-27 Guido Falk von Rudorff , O. Anatole von Lilienfeld

We analyse a nonadiabatic self-consistent field method by means of an exactly-solvable model. The method is based on nuclear and electronic orbitals that are functions of the cartesian coordinates in the laboratory-fixed frame. The kinetic…

Quantum Physics · Physics 2012-12-27 Paolo Amore , Francisco M. Fernández

Traditional multiconfiguration Hartree-Fock (MCHF) and configuration interaction (CI) methods are based on a single orthonormal orbital basis (OB). For atoms with complicated shell structures, a large OB is needed to saturate all the…

Atomic Physics · Physics 2015-06-12 S. Verdebout , P. Rynkun , P. Jönsson , G. Gaigalas , C. Froese Fischer , M. Godefroid

Convex relaxations of the AC Optimal Power Flow (OPF) problem are essential not only for identifying the globally optimal solution but also for enabling the use of OPF formulations in Bilevel Programming and Mathematical Programs with…

Optimization and Control · Mathematics 2020-06-23 Lucien Bobo , Andreas Venzke , Spyros Chatzivasileiadis

The structure of nucleon self-energy in nuclear matter is evaluated for various realistic models of the nucleon-nucleon (NN) interaction. Starting from the Brueckner-Hartree-Fock approximation without the usual angle-average approximation,…

Nuclear Theory · Physics 2009-11-07 T. Frick , Kh. Gad , H. Müther , P. Czerski

The nuclear many-body problem for medium-mass systems is commonly addressed using wave-function expansion methods that build upon a second-quantized representation of many-body operators with respect to a chosen computational basis. While…

Nuclear Theory · Physics 2021-02-02 J. Hoppe , A. Tichai , M. Heinz , K. Hebeler , A. Schwenk

Self-consistent approaches to superfluid many-fermion systems in 3-dimensions (and subsequent time-dependent approaches) require a large number of diagonalizations of very large dimension hermitian matrices, which results in enormous…

Nuclear Theory · Physics 2017-04-12 Shi Jin , Aurel Bulgac , Kenneth Roche , Gabriel Wlazłowski

We calculate the explicit equations of motion for non-spinning compact objects to 2.5 post-Newtonian order, or O(v/c)^5 beyond Newtonian gravity, in a general class of scalar-tensor theories of gravity. We use the formalism of the Direct…

General Relativity and Quantum Cosmology · Physics 2013-05-14 Saeed Mirshekari , Clifford M. Will

Recent works in deep learning have shown that integrating differentiable physics simulators into the training process can greatly improve the quality of results. Although this combination represents a more complex optimization task than…

Machine Learning · Computer Science 2022-03-22 Patrick Schnell , Philipp Holl , Nils Thuerey

We propose an efficient procedure to obtain Green's functions by combining the shifted conjugate orthogonal conjugate gradient (shifted COCG) method with the nonequilibrium Green's function (NEGF) method based on a real-space…

Computational Physics · Physics 2015-02-03 Shigeru Iwase , Takeo Hoshi , Tomoya Ono

We survey approaches to nonrelativistic density functional theory (DFT) for nuclei using progress toward ab initio DFT for Coulomb systems as a guide. Ab initio DFT starts with a microscopic Hamiltonian and is naturally formulated using…

Nuclear Theory · Physics 2009-12-04 J. E. Drut , R. J. Furnstahl , L. Platter

In this paper, an implicit nonsymplectic exact energy-preserving integrator is specifically designed for a ten-dimensional phase-space conservative Hamiltonian system with five degrees of freedom. It is based on a suitable…

General Relativity and Quantum Cosmology · Physics 2021-04-16 Shiyang Hu , Xin Wu , Enwei Liang

State-specific orbital optimized approaches are more accurate at predicting core-level spectra than traditional linear-response protocols, but their utility had been restricted on account of the risk of `variational collapse' down to the…

The energy of a compact binary system at the fifth post-Newtonian order is explicitly computed in the post-Minkowskian approximation by means of the Effective Field Theory approach. This result allows to determine, for the first time beyond…

General Relativity and Quantum Cosmology · Physics 2014-01-27 Stefano Foffa