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Iron-sulfur clusters comprise an important functional motif of the catalytic centers of biological systems, capable of enabling important chemical transformations at ambient conditions. This remarkable capability derives from a notoriously…

Analytic energy gradients are presented for a variational two-electron reduced-density-matrix-driven complete active space self-consistent field (v2RDM-CASSCF) procedure that employs the density-fitting (DF) approximation to the…

Chemical Physics · Physics 2018-11-29 J. Wayne Mullinax , Evgeny Epifanovsky , Gergely Gidofalvi , A. Eugene DePrince

19F isotropic chemical shifts for alkali, alkaline earth and rare earth of column 3 basic fluorides are measured and the corresponding isotropic chemical shieldings are calculated using the GIPAW method. When using PBE exchange correlation…

Chemical accuracy serves as an important metric for assessing the effectiveness of the numerical method in Kohn--Sham density functional theory. It is found that to achieve chemical accuracy, not only the Kohn--Sham wavefunctions but also…

Computational Physics · Physics 2023-10-25 Yang Kuang , Yedan Shen , Guanghui Hu

In large-scale quantum-chemical calculations the electron-repulsion integral (ERI) tensor rapidly becomes the bottleneck in terms of memory and disk space. When an external finite magnetic field is employed, this problem becomes even more…

Chemical Physics · Physics 2022-02-16 Simon Blaschke , Stella Stopkowicz

The physical reason why one can calculate with similar accuracy, as compared to the experimental data, the absolute cross section associated with two-nucleon transfer processes between members of pairing rotational bands, making use of…

Nuclear Theory · Physics 2017-09-20 G. Potel , A. Idini , F. Barranco , E. Vigezzi , R. A. Broglia

The nuclear magnetic shielding is considered within the fully relativistic approach for the ground state of H-, Li-, and B-like ions in the range Z=32-92. The interelectronic interaction is evaluated to the first order of the perturbation…

Atomic Physics · Physics 2021-08-30 A. M. Volchkova , D. A. Glazov , V. M. Shabaev

A multiscale model based on the coupling of the multiconfigurational self-consistent field (MCSCF) method and the classical atomistic polarizable Fluctuating Charges (FQ) force field is presented. The resulting MCSCF/FQ approach is…

We test the AdS/CFT correspondence by computing the partition function of some $\mathcal{N}=2$ quiver Chern-Simons-matter theories on three-sphere. The M-theory backgrounds are of the Freund-Rubin type with the seven-dimensional internal…

High Energy Physics - Theory · Physics 2017-09-07 Sangmo Cheon , Hyojoong Kim , Nakwoo Kim

The nuclear magnetic resonance (NMR) spectrum of spin-3/2 nuclei in a static magnetic field aligned with one of the electric field gradient (EFG) principal axes is developed analytically, based on fictitious spin-1/2 formalism. Compact…

Superconductivity · Physics 2024-12-17 Jaafar N. Ansari , Karen L. Sauer

For the interpretation of spectra of magnetic stellar objects such as magnetic white dwarfs (WDs) highly accurate quantum chemical predictions for atoms and molecules in finite magnetic field are required. Especially the accurate…

Chemical Physics · Physics 2024-10-01 Simon Blaschke , Marios-Petros Kitsaras , Stella Stopkowicz

We present a numerical implementation of the infinite-range exterior complex scaling (irECS) [Phys. Rev. A 81, 053845 (2010)] as an efficient absorbing boundary to the time-dependent complete-active-space self-consistent field (TD-CASSCF)…

Atomic Physics · Physics 2018-03-07 Yuki Orimo , Takeshi Sato , Armin Scrinzi , Kenichi L. Ishikawa

The accurate resolution of the chemical properties of strongly correlated systems, such as biradicals, requires the use of electronic structure theories that account for both multi-reference as well as dynamic correlation effects. A variety…

Chemical Physics · Physics 2023-01-03 Jan-Niklas Boyn , David A. Mazziotti

Complete active space self-consistent field (CASSCF) computations can be realized at polynomial cost via the variational optimization of the active-space two-electron reduced-density matrix (2-RDM). Like conventional approaches to CASSCF,…

Chemical Physics · Physics 2018-12-10 Mohammad Mostafanejad , A. Eugene DePrince

The CGMF code implements the Hauser-Feshbach statistical nuclear reaction model to follow the de-excitation of fission fragments by successive emissions of prompt neutrons and $\gamma$ rays. The Monte Carlo technique is used to facilitate…

Nuclear Theory · Physics 2021-08-09 P. Talou , I. Stetcu , P. Jaffke , M. E. Rising , A. E. Lovell , T. Kawano

We present a real-space adaptive-coordinate method, which combines the advantages of the finite-difference approach with the accuracy and flexibility of the adaptive coordinate method. The discretized Kohn-Sham equations are written in…

mtrl-th · Physics 2009-10-28 Francois Gygi , Giulia Galli

Kohn-Sham density functional theory (KS-DFT) has found widespread application in accurate electronic structure calculations. However, it can be computationally demanding especially for large-scale simulations, motivating recent efforts…

Computational Physics · Physics 2024-06-25 Feitong Song , Ji Feng

In this study, we develop and implement a specialized coupled-cluster (CC) approach tailored for accurately describing atoms and molecules in strong magnetic fields. Using the open-source Ghent Quantum Chemistry Package (\texttt{GQCP}) in…

Atomic Physics · Physics 2025-07-14 T. Zalialiutdinov , D. Solovyev

Density matrix perturbation theory [Niklasson and Challacombe, Phys. Rev. Lett. 92, 193001 (2004)] is generalized to canonical (NVT) free energy ensembles in tight-binding, Hartree-Fock or Kohn-Sham density functional theory. The canonical…

Chemical Physics · Physics 2015-12-09 Anders M. N. Niklasson , Marc J. Cawkwell , Emanuel H. Rubensson , Elias Rudberg

We report $^{133}$Cs nuclear magnetic resonance (NMR) measurements on the 2D frustrated Heisenberg antiferromagnet Cs$_2$CuCl$_4$ down to 2 K and up to 15 T. We show that $^{133}$Cs NMR is a good probe of the magnetic degrees of freedom in…

Strongly Correlated Electrons · Physics 2009-11-11 M. -A. Vachon , W. Kundhikanjana , A. Straub , V. F. Mitrović , A. P. Reyes , P. Kuhns , R. Coldea , Z. Tylczynski