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Partial atomic charges are a useful and intuitive concept for understanding molecular properties and chemical reaction mechanisms, showing how changes in molecular geometry can affect the flow of electronic charge within a molecule.…

Chemical Physics · Physics 2022-01-14 Ryan J. MacDonell , Serguei Patchkovskii , Michael S. Schuurman

A systematic method for determining correlated wavefunctions of extended systems in the ground and excited states is presented. It allows to fully exploit the power of quantum-chemical programs designed for correlation calculations of…

Other Condensed Matter · Physics 2007-05-23 V. Bezugly

We present the first single-reference calculations of the atomic axial tensors (AATs) using wave-function-based methods including dynamic electron correlation effects using second-order M{\o}ller-Plesset perturbation theory (MP2) and…

Chemical Physics · Physics 2024-06-11 Brendan M. Shumberger , T. Daniel Crawford

We propose an algorithm for low Mach number reacting flows subjected to electric field that includes the chemical production and transport of charged species. This work is an extension of a multi-implicit spectral deferred correction…

Fluid Dynamics · Physics 2020-06-24 Lucas Esclapez , Valentina Ricchiuti , John B. Bell , Marcus S. Day

We report internally contracted relativistic multireference configuration interaction (ic-MRCI), complete active space second-order perturbation (CASPT2), and strongly contracted n-electron valence state perturbation theory (NEVPT2) on the…

Chemical Physics · Physics 2015-12-31 Toru Shiozaki , Wataru Mizukami

Eigenvector continuation (EC) has recently attracted a lot attention in nuclear structure and reactions as a variational resummation tool for many-body expansions. While previous applications focused on ground-state energies, excited states…

Nuclear Theory · Physics 2022-06-09 Margarida Companys Franzke , Alexander Tichai , Kai Hebeler , Achim Schwenk

Efficiently recovering dynamic correlation in strongly correlated systems without incurring prohibitive computational costs remains a central challenge in quantum chemistry. In this Perspective, we review and benchmark methods capable of…

Chemical Physics · Physics 2026-05-22 Michał Hapka , Aleksandra Tucholska , Katarzyna Pernal

We present a comprehensive study of low-lying states in even-even Ne, Mg, Si, S, Ar isotopes with the multireference density functional theory (MR-DFT) based on a relativistic point-coupling energy density functional (EDF). Beyond…

Nuclear Theory · Physics 2015-12-09 Xian-Ye Wu , Xian-Rong Zhou

A first principles quantum formalism to describe the non-adiabatic dynamics of electrons and nuclei based on a second quantization representation (SQR) of the electronic motion combined with the usual representation of the nuclear…

Chemical Physics · Physics 2020-11-06 Sudip Sasmal , Oriol Vendrell

We discuss an efficient approach to excited electronic states within ab-initio many-body perturbation theory (MBPT). Quasiparticle corrections to density-functional theory result from the difference between metallic and non-metallic…

Materials Science · Physics 2013-05-29 Michael Rohlfing

Localized molecular orbitals are often used for the analysis of chemical bonds, but they can also serve to efficiently and comprehensibly compute linear response properties. While conventional canonical molecular orbitals provide an…

Chemical Physics · Physics 2023-02-08 Souloke Sen , Bruno Senjean , Lucas Visscher

Processes related to electronically excited states are central in many areas of science, however accurately determining excited-state energies remains a major challenge in theoretical chemistry. Recently, higher energy stationary states of…

Chemical Physics · Physics 2020-06-05 Hugh G. A. Burton , Alex J. W. Thom , Pierre-François Loos

We present a mean field theory for excited states that is broadly analogous to ground state Hartree-Fock theory. Like Hartree-Fock, our approach is deterministic, state-specific, applies a variational principle to a minimally correlated…

Strongly Correlated Electrons · Physics 2018-08-28 Jacqueline A. R. Shea , Eric Neuscamman

This paper describes a method to do ab initio molecular dynamics in electronically excited systems within the random phase approximation (RPA). Using a dynamical variational treatment of the RPA frequency, which corresponds to the…

Condensed Matter · Physics 2009-10-31 Eric R. Bittner , D. S. Kosov

An electrodynamical coupled cluster (CC) methodology starting from a covariant formalism and an equal time approximation, and finally based on the Dirac-Fock picture of the electron and positron fields and Coulomb gauge, is given here. The…

Atomic Physics · Physics 2019-04-30 Sambhu N. Datta

We present a multiscale quantum-defect theory based on the first analytic solution for a two-scale long range potential consisting of a Coulomb potential and a polarization potential. In its application to atomic structure, the theory…

Atomic Physics · Physics 2016-10-25 Haixiang Fu , Mingzhe Li , Meng Khoon Tey , Li You , Bo Gao

Spectroscopic properties of molecules holds great importance for the description of the molecular response under the effect of an UV/Vis electromagnetic radiation. Computationally expensive ab initio (e.g. MultiConfigurational SCF, Coupled…

We construct, analyse and assess various schemes of second order of accuracy in space and time for model advection-diffusion-reaction differential equations. The constructed schemes are meant to be of practical use in solving industrial…

Numerical Analysis · Mathematics 2023-01-25 Saray Busto , Eleuterio F. Toro , Maria Elena Vazquez-Cendon

Molecules that have been suggested to violate the Hund's rule, having a first excited singlet state (S$_1$) energetically below the triplet state (T$_1$), are rare. Yet, they hold the promise to be efficient light emitters. Their…

Chemical Physics · Physics 2025-09-23 Atreyee Majumdar , Raghunathan Ramakrishnan