Nuclear charge distribution effects in shielding and spin-rotation constants within a relativistic framework

IGNACIO AGUSTIN AUCAR; CARLOS A. GIMENEZ; GUSTAVO A. AUCAR

Malburg

Congreso; Relativistic effects on heavy elements REHE XII; 2017

Comité organizador local e internacional

The nuclear charge distribution effects on two molecular properties, NMR shieldings and nuclear spin-rotation (SR) constants, are analyzed employing point-like and Gaussian nuclear models in order to describe the electron-nucleus interaction. According to our results, both properties are sensitive to the NChDE. We show that NChDE are of relativistic nature, i.e., they only appear when calculations of both properties are carriedout within a relativistic framework. These effects are analyzed in three linear molecules: HBr, HI and HAt. The NChDE on shielding constants are studied on the grounds of a recently proposed relativistic relation between this property and the SR constant. Using that relation, we arrive to an important finding: the NChDE are mainly due to core mechanisms, which are present in the shielding of nuclei in a molecule and in a free atom. The NChDE are smaller on SR constants than on the shieldings. Furthermore, the NChDE are very important for SR constants of nuclei in heavy-atom-containing compounds. This is the case of astatine in HAt, where the four-component calculation gives 0.31 kHz using a point-like model, though it gives -41.01 kHz when a Gaussian nuclear model is employed.