Ignacio Agustín Aucar

Ignacio Agustín Aucar
National Scientific and Technical Research Council | conicet · IMIT Instituto de Modelado e Innovación Tecnológica

About

17
Publications
1,813
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
287
Citations
Additional affiliations
March 2015 - present
National University of the Northeast
Position
  • Professor (Assistant)
January 2011 - present
Institute for Modeling and Innovative Technology IMIT
Position
  • Universidad Nacional del Nordeste

Publications

Publications (17)
Article
The indirect spin-spin coupling tensor, $\bm J$, between mercury nuclei in systems containing this element can be of the order of few kHz and one of the largest measured. We analysed the physics behind the electronic mechanisms that contribute to the one- and two-bond couplings $^n \bm{J}_{\mathrm{Hg}-\mathrm{Hg}}$ ($n=1, 2$). For doing so, we perf...
Preprint
Full-text available
The indirect nuclear spin-spin coupling tensor, $\bm J$, between mercury nuclei in Hg-containing systems can be of the order of few kHz and one of the largest measured. We conduct an analysis of the physics behind the electronic mechanisms that contribute to the one- and two-bond couplings $^n {\bm J}_{\mathrm{Hg}-\mathrm{Hg}}$ ($n=1, 2$). We perfo...
Article
We present a four-component relativistic approach to describe the effects of the nuclear spin-dependent parity-violating (PV) weak nuclear forces on nuclear spin-rotation (NSR) tensors. The formalism is derived within the four-component polarization propagator theory based on the Dirac–Coulomb Hamiltonian. Such calculations are important for planni...
Article
The nonrelativistic “Ramsey-Flygare relationship” is the most used procedure to obtain semiexperimental nuclear magnetic resonance (NMR) absolute shieldings by a correspondence between NMR shieldings (σ) and nuclear spin-rotation constants (M). One of its generalizations to the relativistic framework is known as the M-V model, which was proposed fe...
Article
Full-text available
DIRAC is a freely distributed general-purpose program system for one-, two-, and four-component relativistic molecular calculations at the level of Hartree–Fock, Kohn–Sham (including range-separated theory), multiconfigurational self-consistent-field, multireference configuration interaction, electron propagator, and various flavors of coupled clus...
Preprint
Full-text available
DIRAC is a freely distributed general-purpose program system for 1-, 2- and 4-component relativistic molecular calculations at the level of Hartree--Fock, Kohn--Sham (including range-separated theory), multiconfigurational self-consistent-field, multireference configuration interaction, coupled cluster and electron propagator theory. At the self-co...
Code
DIRAC19 DIRAC, a relativistic ab initio electronic structure program, Release DIRAC19 (2019), written by A. S. P. Gomes, T. Saue, L. Visscher, H. J. Aa. Jensen, and R. Bast, with contributions from I. A. Aucar, V. Bakken, K. G. Dyall, S. Dubillard, U. Ekström, E. Eliav, T. Enevoldsen, E. Faßhauer, T. Fleig, O. Fossgaard, L. Halbert, E. D. Hedegård,...
Article
We show here results of four-component calculations of nuclear magnetic resonance σ for atoms with 10 ≤ Z ≤ 86 and their ions, within the polarization propagator formalism at its random phase level of approach, and the first estimation of quantum electrodynamic (QED) effects and Breit interactions of those atomic systems by using two theoretical ef...
Chapter
The absolute value of the nuclear magnetic shielding tensor, σ cannot be directly measured as such, though at the moment experimental devices are available to obtain them by extrapolation to zero-density limit. This is the reason why since the beginning of NMR spectroscopy to obtain the experimental values of this parameter required the interplay b...
Article
Full-text available
The nuclear charge distribution effects (NChDE) on two response properties, the NMR magnetic shielding (σ) and the nuclear spin-rotation (SR) constants (M), are analyzed. We do it employing point-like and Gaussian-like models for describing the nuclear charge density of three linear molecules: HBr, HI and HAt. According to our results, both propert...
Article
Full-text available
Accurate calculations of some response properties, like the NMR spectroscopic parameters, are quite exigent for the theoretical quantum chemistry models together with the computational codes that are written from them. They need to include a very good description of the electronic density in regions close to the nuclei. When heavy-atom containing s...
Article
Full-text available
The broadly accepted procedure to obtain the experimental absolute scale of NMR magnetic shieldings, $\sigma$, is well known for non-heavy atom containing molecules. It was uncovered more than forty years ago by the works of Ramsey and Flygare. They found a quite accurate relationship among $\sigma$ and the nuclear spin-rotation constants. Its rela...
Article
Full-text available
One of the most influential articles showing the best way to get the absolute values of NMR magnetic shieldings, σ (non-measurables) from both accurate measurements and theoretical calculations, was published a long time ago by Flygare. His model was shown to break down when heavy atoms are involved. This fact motivated the development of new theor...
Article
An original formulation of the relativistic molecular rotational g-tensor valid for heavy atom containing compounds is presented. In such formulation, the relevant terms of a molecular Hamiltonian for non-relativistic nuclei and relativistic electrons in the laboratory system are considered. Terms linear and bilinear in the nuclear rotation angular...
Article
In this work, relativistic effects on the nuclear spin-rotation (SR) tensor originated in the electron-nucleus and electron-electron Breit interactions are analysed. To this end, four-component numerical calculations were carried out in model systems HX (X=H,F,Cl,Br,I). The electron-nucleus Breit interaction couples the electrons and nuclei dynamic...
Article
In the present work, numerical results of the nuclear spin-rotation (SR) tensor in the series of compounds HX (X=H,F,Cl,Br,I) within relativistic 4-component expressions obtained by Aucar et al. [J. Chem. Phys. 136, 204119 (2012)] are presented. The SR tensors of both the H and X nuclei are discussed. Calculations were carried out within the relati...
Article
A theoretical study of the relation between the relativistic formulation of the nuclear magnetic shielding and spin-rotation tensors is presented. To this end a theoretical expression of the relativistic spin-rotation tensor is formulated, considering a molecular Hamiltonian of relativistic electrons and non-relativistic nuclei. Molecular rotation...

Network

Cited By