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The projection-based quantum embedding method is applied to electronically excited states of valence, Rydberg, and charge-transfer character, valence- and core-ionized states, as well as bound and temporary radical anions. We embed…

Chemical Physics · Physics 2021-06-10 Valentina Parravicini , Thomas-C. Jagau

The Coupled Cluster (CC) method is used to compute the electronic correlation energy in atoms and molecules and often leads to highly accurate results. However, due to its single-reference nature, standard CC in its projected form fails to…

We report the first investigation of the performance of EOM-CC4 -- an approximate equation-of-motion coupled-cluster model which includes iterative quadruple excitations -- for vertical excitation energies in molecular systems. By…

Chemical Physics · Physics 2021-06-14 Pierre-François Loos , Devin A. Matthews , Filippo Lipparini , Denis Jacquemin

This paper studies the numerical approximation of parametric time-dependent partial differential equations (PDEs) by proper orthogonal decomposition reduced order models (POD-ROMs). Although many papers in the literature consider reduced…

Numerical Analysis · Mathematics 2025-04-28 Bosco García-Arcilla , Alicia García-Mascaraque , Julia Novo

The convergent close-coupling method is applied to the calculation of fully differential cross sections for ionization of atomic hydrogen by 15.6 eV electrons. We find that even at this low energy the method is able to yield predictive…

Atomic Physics · Physics 2009-10-31 Igor Bray

We scrutinize the performance of different variants of equation of motion coupled cluster (EOM-CC) methods to predict electronic excitation energies and excited state potential energy surfaces in closed-shell actinide species. We focus our…

Chemical Physics · Physics 2020-02-26 Artur Nowak , Paweł Tecmer , Katharina Boguslawski

The ionization potential (IP) is an important parameter providing essential insights into the reactivity of chemical systems. IPs are also crucial for designing, optimizing, and understanding the functionality of modern technological…

Chemical Physics · Physics 2024-02-12 Marta Gałyńska , Katharina Boguslawski

We present a comprehensive theoretical study of the ionization potentials of the MF (M = Sc, Y, La, Ac) molecules using the state-of-the-art relativistic coupled cluster approach with single, double, and perturbative triple excitations…

We compare the predictions of four different algorithms for the distribution of ionized gas during the Epoch of Reionization. These algorithms are all used to run a 100 Mpc/h simulation of reionization with the same initial conditions. Two…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Oliver Zahn , Andrei Mesinger , Matthew McQuinn , Hy Trac , Renyue Cen , Lars E. Hernquist

We report the general implementation of the relativistic equation-of-motion coupled-cluster method to calculate double ionization spectra (DI-EOMCC) of atomic and molecular systems. As a first application, this method is employed to…

Atomic Physics · Physics 2014-08-25 Himadri Pathak , Aryya Ghosh , B. K. Sahoo , B. P. Das , Nayana Vaval , Sourav Pal

Through detailed comparisons between Embedded Atom Method (EAM) and first-principles calculations for Al, we find that EAM tends to fail when there are large electron density gradients present. We attribute the observed failures to the…

Mesoscale and Nanoscale Physics · Physics 2009-01-30 Gang Wu , Gang Lu , Carlos J. Garcia-Cervera , Weinan E

Constant potential method molecular dynamics simulation (CPM MD) enables the accurate modelling of atomistic electrode charges when studying the electrode-electrolyte interface at the nanoscale. Here we extend the theoretical framework of…

Materials Science · Physics 2023-05-26 Shern Ren Tee , Debra J. Searles

In the framework of the computational determination of highly-accurate vertical excitation energies in small organic compounds, we explore the possibilities offered by the equation-of-motion formalism relying on the approximate fourth-order…

We present an implementation of equation of motion coupled-cluster singles and doubles (EOM-CCSD) theory using periodic boundary conditions and a plane wave basis set. Our implementation of EOM-CCSD theory is applied to study $F$-centers in…

Materials Science · Physics 2021-02-09 Alejandro Gallo , Felix Hummel , Andreas Irmler , Andreas Grüneis

Large scale atomistic simulations with suitable interatomic potentials are widely employed by scientists or engineers of different areas. Quick generation of high-quality interatomic potentials is of urgent need under present circumstances,…

Materials Science · Physics 2016-11-23 Kun Wang , Wenjun Zhu , Shifang Xiao , Jun Chen , Wangyu Hu

We report an implementation of the core-valence separation approach to the 4-component relativistic Hamiltonian based equation-of-motion coupled-cluster with singles and doubles theory (CVS-EOM-CCSD), for the calculation of relativistic…

We discuss the application of Widom insertion method for calculation of the chemical potential of individual ions in computer simulations with Ewald summation. Two approaches are considered. In the first approach, an individual ion is…

Soft Condensed Matter · Physics 2022-03-21 Amin Bakhshandeh , Yan Levin

Problems in quantum chemical simulations, especially achieving accurate excited-state potential energy surfaces, are among the primary applications to achieve quantum utility. On near-term quantum hardware, variants of the variational…

A well known, if little documented, problem in many molecular simulations of aqueous ionic solutions at finite concentrations is that unrealistic cation-cation associations are frequently found. One might suspect a defect in the ion-ion…

Soft Condensed Matter · Physics 2012-07-16 Ph. A. Bopp , K. Ibuki

The values of ion-atom ionization cross sections are frequently needed for many applications that utilize the propagation of fast ions through matter. When experimental data and theoretical calculations are not available, approximate…

Atomic Physics · Physics 2008-11-26 Igor D. Kaganovich , Edward Startsev , Ronald C. Davidson