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norskBlar i forfatter Artikler, rapporter og annet (kjemi) "Repisky, Michal"
Viser treff 21-32 av 32
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Implementation of Relativistic Coupled Cluster Theory for Massively Parallel GPU-Accelerated Computing Architectures
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-08-09)In this paper, we report reimplementation of the core algorithms of relativistic coupled cluster theory aimed at modern heterogeneous high-performance computational infrastructures. The code is designed for parallel execution on many compute nodes with optional GPU coprocessing, accomplished via the new ExaTENSOR back end. The resulting ExaCorr module is primarily intended for calculations of molecules ... -
Indirect NMR spin-spin coupling constants in diatomic alkali halides
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-12-28)We report the Nuclear Magnetic Resonance (NMR) spin–spin coupling constants for diatomic alkali halides MX, where M = Li, Na, K, Rb, or Cs and X = F, Cl, Br, or I. The coupling constants are determined by supplementing the non-relativistic coupled-cluster singles-and-doubles (CCSD) values with relativistic corrections evaluated at the four-component density-functional theory (DFT) level. These ... -
Linking the Character of the Metal-Ligand Bond to the Ligand NMR Shielding in Transition-Metal Complexes: NMR Contributions from Spin-Orbit Coupling
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-07-06)Relativistic effects significantly affect various spectroscopic properties of compounds containing heavy elements. Particularly in Nuclear Magnetic Resonance (NMR) spectroscopy, the heavy atoms strongly influence the NMR shielding constants of neighboring light atoms. In this account we analyze paramagnetic contributions to NMR shielding constants and their modulation by relativistic spin–orbit ... -
Relativistic DFT Calculations of Hyperfine Coupling Constants in 5d Hexafluorido Complexes: [ReF6]2- and [IrF6]2-
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-10-12)The performance of relativistic density functional theory (DFT) methods has been investigated for the calculation of the recently measured hyperfine coupling constants of hexafluorido complexes [ReF<sub>6</sub> ] <sup>2-</sup> and [IrF<sub>6</sub> ] <sup>2-</sup> . Three relativistic methods were employed at the DFT level of theory: the 2-component zeroth-order regular approximation ... -
Relativistic four-component calculations of indirect nuclear spin-spin couplings with efficient evaluation of the exchange-correlation response kernel
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-03-16)In this work, we report on the development and implementation of a new scheme for efficient calculation of indirect nuclear spin-spin couplings in the framework of four-component matrix Dirac-Kohn-Sham approach termed matrix Dirac-Kohn-Sham restricted magnetic balance resolution of identity for J and K, which takes advantage of the previous restricted magnetic balance formalism and the density ... -
Relativistic four-component linear damped response TDDFT for electronic absorption and circular dichroism calculations
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11-21)We present a detailed theory, implementation, and a benchmark study of a linear damped response time-dependent density functional theory (TDDFT) based on the relativistic four-component (4c) Dirac–Kohn–Sham formalism using the restricted kinetic balance condition for the small-component basis and a noncollinear exchange–correlation kernel. The damped response equations are solved by means of a ... -
Resolution-of-identity accelerated relativistic two- and four-component electron dynamics approach to chiroptical spectroscopies
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-27)We present an implementation and application of electron dynamics based on real-time time-dependent density functional theory (RT-TDDFT) and relativistic 2-component X2C and 4-component Dirac–Coulomb (4c) Hamiltonians to the calculation of electron circular dichroism and optical rotatory dispersion spectra. In addition, the resolution-of-identity approximation for the Coulomb term (RI-J) is introduced ... -
ReSpect: Relativistic spectroscopy DFT program package
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-11)With the increasing interest in compounds containing heavier elements, the experimental and theoretical community requires computationally efficient approaches capable of simultaneous non-perturbative treatment of relativistic, spin-polarization, and electron correlation effects. The ReSpect program has been designed with this goal in mind and developed to perform relativistic density functional ... -
Spin-rotation and NMR shielding constants in HCl
(Journal article; Tidsskriftartikkel; Peer reviewed, 2013)The spin-rotation and nuclear magnetic shielding constants are analysed for both nuclei in the HCl molecule. Nonrelativistic ab initio calculations at the CCSD(T) level of approximation show that it is essential to include relativistic effects to obtain spin-rotation constants consistent with accurate experimental data. Our best estimates for the spin-rotation constants of 1H35Cl are CCl =−53.914 ... -
Structure, solvent, and relativistic effects on the NMR chemical shifts in square-planar transition-metal complexes: Assessment of DFT approaches
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-08-25)The role of various factors (structure, solvent, and relativistic treatment) was evaluated for square-planar 4d and 5d transition-metal complexes. The DFT method for calculating the structures was calibrated using a cluster approach and compared to X-ray geometries, with the PBE0 functional (def2-TZVPP basis set) providing the best results, followed closely by the hybrid TPSSH and the MN12SX ... -
Supramolecular coronation of platinum(II) complexes by macrocycles: Structure, relativistic DFT calculations, and biological effects
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-05)Platinum-based anticancer drugs are actively developed utilizing lipophilic ligands or drug carriers for the efficient penetration of biomembranes, reduction of side effects, and tumor targeting. We report the development of a supramolecular host–guest system built on cationic platinum(II) compounds bearing ligands anchored in the cavity of the macrocyclic host. The host–guest binding and hydrolysis ... -
X-ray absorption resonances near L2,3-edges from real-time propagation of the Dirac–Kohn–Sham density matrix
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-08-07)The solution of the Liouville–von Neumann equation in the relativistic Dirac–Kohn–Sham density matrix formalism is presented and used to calculate X-ray absorption cross sections. Both dynamical relaxation effects and spin–orbit corrections are included, as demonstrated by calculations of the X-ray absorption of SF6 near the sulfur L2,3-edges. We also propose an analysis facilitating the interpretation ...
