Influence of the nuclear charge distribution and electron correlation effects on magnetic shieldings and spin-rotation tensors of linear molecules.

Autor: Aucar IA; Instituto de Modelado e Innovación Tecnológica, CONICET, Departamento de Física - Facultad de Ciencias Exactas y Naturales, UNNE Av. Libertad 5460, W3404AAS Corrientes Argentina agustin.aucar@conicet.gov.ar., Giménez CA; Instituto de Modelado e Innovación Tecnológica, CONICET, Departamento de Física - Facultad de Ciencias Exactas y Naturales, UNNE Av. Libertad 5460, W3404AAS Corrientes Argentina agustin.aucar@conicet.gov.ar., Aucar GA; Instituto de Modelado e Innovación Tecnológica, CONICET, Departamento de Física - Facultad de Ciencias Exactas y Naturales, UNNE Av. Libertad 5460, W3404AAS Corrientes Argentina agustin.aucar@conicet.gov.ar.
Jazyk: angličtina
Zdroj: RSC advances [RSC Adv] 2018 Jun 04; Vol. 8 (36), pp. 20234-20249. Date of Electronic Publication: 2018 Jun 04 (Print Publication: 2018).
DOI: 10.1039/c8ra03948h
Abstrakt: 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 properties are sensitive to the NChDE. We show that the NChDE are almost completely relativistic, i.e. , they nearly vanish in the non-relativistic limit of both properties. We calculated the NChDE on σ and M , and analyzed the differences between them in terms of a relativistic relation between these two properties. Using that relation we found that the electronic core mechanisms are the main ones for the NChDE on the shielding of nuclei of both, molecules and free atoms. The NChDE are smaller on SR constants than on shieldings. Nevertheless, within the relativistic polarization propagator formalism at the RPA level of approach they are very important for SR constants of nuclei in heavy-atom-containing compounds. Astatine in HAt has the largest influence: M At = -9.95 kHz for a point-like model and -50.10 kHz for a Gaussian-like model. Correlation effects must be included and we do it using different DFT schemes. The PBE0 functional gives results that are closest to experiments for Br and I, though the LDA gives the closest for hydrogen. The value of the SR constant of At is reduced among 350 kHz and 500 kHz from its RPA value, when different and usual functionals are applied. Given that the NChDE on M and σ are mostly relativistic in their origin, these effects are also dependent on electron correlation. They have also a nonvanishing dependence with the Gaunt electron-electron interactions.
Competing Interests: There are no conflicts of interest to declare.
(This journal is © The Royal Society of Chemistry.)
Databáze: MEDLINE
Externí odkaz: