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Related papers: Orbital Optimization in the Active Space Decomposi…

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Ab initio molecular dynamics (AIMD) with hybrid density functionals and plane wave basis is computationally expensive due to the high computational cost of exact exchange energy evaluation. Recently, we proposed a strategy to combine…

Chemical Physics · Physics 2021-01-11 Sagarmoy Mandal , Vaishali Thakkur , Nisanth N. Nair

Computation of electronic spectra is one of the most important applications of methods capturing static electron correlation, including complete-active-space self-consistent field (CASSCF) and post-CASSCF theories. Performance of these…

Chemical Physics · Physics 2025-11-19 Reza G. Shirazi , Alexander Zech , Peter Pinski , Vladimir V. Rybkin

The scientific computation methods development in conjunction with artificial intelligence technologies remains a hot research topic. Finding a balance between lightweight and accurate computations is a solid foundation for this direction.…

Machine Learning · Computer Science 2025-07-03 Nikita Sakovich , Dmitry Aksenov , Ekaterina Pleshakova , Sergey Gataullin

The issue of orbital relaxation in computational core-hole spectroscopy, specifically x-ray absorption, has been a major problem for methods such as equation-of-motion coupled cluster with singles and doubles (EOM-CCSD). The…

Chemical Physics · Physics 2025-03-26 Megan Simons , Devin A. Matthews

We propose a new algorithm to compute a shifted proper orthogonal decomposition (sPOD) for systems dominated by multiple transport velocities. The sPOD is a recently proposed mode decomposition technique which overcomes the poor performance…

Numerical Analysis · Mathematics 2018-03-06 Philipp Schulze , Julius Reiss , Volker Mehrmann

We study several approaches to orbital optimization in selected configuration interaction plus perturbation theory (SCI+PT) methods, and test them on the ground and excited states of three molecules using the semistochastic heatbath…

Chemical Physics · Physics 2021-07-14 Yuan Yao , C. J. Umrigar

The accuracy of reaction energy profiles calculated with multi-configurational electronic structure methods and corrected by multi-reference perturbation theory depends crucially on consistent active orbital spaces selected along the…

Chemical Physics · Physics 2023-04-14 Moritz Bensberg , Markus Reiher

Active, selective and stable catalysts are imperative for sustainable energy conversion, and engineering materials with such properties are highly desired. High-entropy alloys (HEAs) offer a vast compositional space for tuning such…

Orbital relaxation of the core region is a primary source of error in the computation of core ionization and core excitation energies. Recently, Transition-Potential Coupled Cluster (TP-CC) methods have been used to explicitly treat orbital…

Chemical Physics · Physics 2025-03-17 Alexis A. A. Delgado , Devin A. Matthews

In contrast to the original Kohn-Sham (KS) formalism, we propose a density functional theory (DFT) with fractional orbital occupations for the study of ground states of many-electron systems, wherein strong static correlation is shown to be…

Chemical Physics · Physics 2015-06-03 Jeng-Da Chai

Mode-based model-reduction is used to reduce the degrees of freedom of high dimensional systems, often by describing the system state by a linear combination of spatial modes. Transport dominated phenomena, ubiquitous in technical and…

Numerical Analysis · Mathematics 2020-02-28 Julius Reiss

Variational optimization of orbitals in time-independent density functional calculations of excited electronic states presents a significant challenge, as excited states typically correspond to saddle points on the electronic energy…

Chemical Physics · Physics 2026-04-02 Yorick L. A. Schmerwitz , Elli Selenius , Gianluca Levi

Functionals that explicitly depend on occupied, unoccupied, or fractionally-occupied orbitals are rigorously formalized using Clifford algebras, and a variational principle is established that facilitates orbital (and occupation)…

Quantum Physics · Physics 2024-04-26 Neil Qiang Su

We present the time-dependent complete-active-space self-consistent-field (TD-CASSCF) method to simulate multielectron dynamics in ultrafast intense laser fields from the first principles. While based on multiconfiguration expansion, it…

Atomic Physics · Physics 2018-04-24 Takeshi Sato , Yuki Orimo , Takuma Teramura , Oyunbileg Tugs , Kenichi L. Ishikawa

Unitary Coupled Cluster (UCC) theory is a promising variational method for electronic structure calculations, especially for strongly correlated systems and quantum computers. However, its practical application is limited by the steep…

Chemical Physics · Physics 2026-02-05 Prateek Vaish , Brenda Rubenstein

Compact objects evolving in an astrophysical environment experience a gravitational drag force known as dynamical friction. We present a multipole-frequency decomposition to evaluate the orbit-averaged energy and angular momentum…

Astrophysics of Galaxies · Physics 2025-09-22 Gali Eytan , Vincent Desjacques , Yonadav Barry Ginat

Intramolecular symmetry-adapted perturbation theory (ISAPT) is a method to compute and decompose the noncovalent interaction energy between two molecular fragments A and B connected via a linker C. The existing ISAPT algorithm displays…

Chemical Physics · Physics 2022-09-13 Du Luu , Konrad Patkowski

Current-spin density functional theory (CSDFT) provides a framework to describe interacting many-electron systems in a magnetic field which couples to both spin- and orbital-degrees of freedom. Unlike in usual (spin-) density functional…

Materials Science · Physics 2015-06-25 S. Pittalis , S. Kurth , N. Helbig , E. K. U. Gross

We developed a general framework for hybrid quantum-classical computing of molecular and periodic embedding approaches based on an orbital space separation of the fragment and environment degrees of freedom. We demonstrate its potential by…

Chemical Physics · Physics 2024-12-23 Stefano Battaglia , Max Rossmannek , Vladimir V. Rybkin , Ivano Tavernelli , Jürg Hutter

We extend the modal decomposition method, previously applied to compress the information in the real-space bispectrum, to the anisotropic redshift-space galaxy bispectrum. In the modal method approach, the bispectrum is expanded on a basis…

Cosmology and Nongalactic Astrophysics · Physics 2022-08-31 Joyce Byun , Elisabeth Krause