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The original formulation (Phys. Rev. Lett. 119, 063002, 2017) of the natural orbital functional - second-order M{\o}ller-Plesset (NOF-MP2) method is based on the MP2 that uses the canonical Hartree-Fock molecular orbitals. The current work…

Chemical Physics · Physics 2018-08-22 Mario Piris

This work presents exchange potentials for specific orbitals calculated by inverting Hartree-Fock wavefunctions. This was achieved by using a Depurated Inversion Method. The basic idea of the method relies upon the substitution of…

Atomic and Molecular Clusters · Physics 2016-10-21 A. M. P. Mendez , D. M. Mitnik , J. E. Miraglia

We address the degree to which machine learning can be used to accurately and transferably predict post-Hartree-Fock correlation energies. Refined strategies for feature design and selection are presented, and the molecular-orbital-based…

Chemical Physics · Physics 2019-04-17 Lixue Cheng , Matthew Welborn , Anders S. Christensen , Thomas F. Miller

We present an implementation of the multiconfiguration time-dependent Hartree-Fock method based on the adaptive finite element method for molecules under intense laser pulses. For efficient simulations, orbital functions are propagated by a…

Quantum Physics · Physics 2023-01-09 Yuki Orimo , Takeshi Sato , Kenichi L. Ishikawa

We demonstrate how to determine numerically nearly exact orthonormal orbitals that are optimal for evaluation of the energy of arbitrary (correlated) states of atoms and molecules by minimization of the energy Lagrangian. Orbitals are…

An efficient computational algorithm to implement a local operator approach to partitioning electronic energy in general molecular systems is presented. This approach, which rigorously defines the electronic energy on any subsystem within a…

Chemical Physics · Physics 2014-01-13 Jayashree Nagesh , Artur F. Izmaylov , Paul Brumer

For the Hirshfeld-I atom-in-molecule model, associated single-atom energies and interaction energies at the Hartree-Fock level are determined efficiently in one-electron Hilbert space. In contrast to most other approaches, the energy terms…

We introduce affordable computational strategies for calculating orbital and pair-orbital energies in atomic and molecular systems. Our methods are based on the pair Coupled Cluster Doubles (pCCD) ansatz and its orbital-optimized variant.…

Chemical Physics · Physics 2025-02-06 Seyedehdelaram Jahani , Somayeh Ahmadkhani , Katharina Boguslawski , Paweł Tecmer

Momentum-space approach to calculation of one-electron energies and wave functions proposed initially by Fock for a hydrogen atom and considered later by Shibuya, Wulfman, and Koga for diatomic molecules is applied to clusters composed of…

Quantum Physics · Physics 2007-05-23 V. F. Elesin , A. I. Podlivaev , L. A. Openov

The precise determination of the excitation energies in condensed-phase molecular systems is important for understanding system-environment interactions as well as for the prerequisite input data of theoretical models used to study the…

Mesoscale and Nanoscale Physics · Physics 2019-10-16 Nguyen Thanh Phuc , Akihito Ishizaki

We present efficient implementations of the multilevel CC2 (MLCC2) and multilevel CCSD (MLCCSD) models. As the system size increases, MLCC2 and MLCCSD exhibit the scaling of the lower level coupled cluster model. In order to treat large…

Chemical Physics · Physics 2020-11-25 Sarai D. Folkestad , Eirik F. Kjønstad , Linda Goletto , Henrik Koch

We present unrestricted Hartree Fock method coupled with configuration interaction (CI) method (URHF-CI) suitable for the calculation of ground and excited states of large number of electrons localized by complex gate potentials in…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Ramin M. Abolfath , Pawel Hawrylak

Electron energy loss spectroscopy is consolidating as a powerful tool to explore electronic (as well as vibrational) excitations of matter, including molecules. Performed in a scanning transmission electron microscope, this technique is…

Chemical Physics · Physics 2021-03-05 Ciro A. Guido , Enzo Rotunno , Matteo Zanfrognini , Stefano Corni , Vincenzo Grillo

The localized operator partitioning method [Y. Khan and P. Brumer, J. Chem. Phys. 137, 194112 (2012)] rigorously defines the electronic energy on any subsystem within a molecule and gives a precise meaning to the subsystem ground and…

Chemical Physics · Physics 2016-10-31 Jayashree Nagesh , Artur F. Izmaylov , Paul Brumer

We derive an automatic procedure for generating a set of highly localized, non-orthogonal orbitals for linear scaling quantum Monte Carlo calculations. We demonstrate the advantage of these orbitals in calculations of the total energy of…

Materials Science · Physics 2007-05-23 F. A. Reboredo , A. J. Williamson

The relativistic Hartree-Fock and electron correlation methods without the negative-energy orbital problem are examined on the basis of the quantum electrodynamics (QED) Hamiltonian. First, several QED Hamiltonians previously proposed are…

Chemical Physics · Physics 2023-01-02 Nobuki Inoue , Yoshihiro Watanabe , Haruyuki Nakano

A new method to determine electron correlation energy is described. This method is based on a better representation of the potential due to interacting electrons that is obtained by specifying both the average and standard deviation. The…

Materials Science · Physics 2007-05-23 T. R. S. Prasanna

We introduce the Deep Post-Hartree-Fock (DeePHF) method, a machine learning based scheme for constructing accurate and transferable models for the ground-state energy of electronic structure problems. DeePHF predicts the energy difference…

Chemical Physics · Physics 2020-08-11 Yixiao Chen , Linfeng Zhang , Han Wang , Weinan E

We present a spin-dependent localized Hartree-Fock (SLHF) density-functional approach for the treatment of the inner-shell excited-state calculation of atomic systems. In this approach, the electron spin-orbitals in an electronic…

Atomic Physics · Physics 2009-11-11 Zhongyuan Zhou , Shih-I Chu

The multilayer multiconfiguration time-dependent Hartree theory within second quantization representation of the Fock space is applied to study correlated electron transport in models of single-molecule junctions. Extending previous work,…

Mesoscale and Nanoscale Physics · Physics 2015-06-12 Haobin Wang , Michael Thoss