Relativistic relationships among response properties

CLAUDIA G. GIRIBET; AUCAR, GUSTAVO A.; AUCAR, I. AGUSTÍN; GOMEZ, SERGIO S.

Marburg

Congreso; 12th International Conference on Relativistic Effects in Heavy-Element Chemistry and Physics; 2017

Phillipps Universitat-Marburg

Some of the most inuential articles showing the best way to obtain the experimentalabsolute scale of NMR magnetic shieldings, (non-measurables) from both accurate mea-surements and theoretical calculations, were published more than forty years ago by Ram-sey and Flygare.[1] The model was shown to break down when heavy atoms are involved.Many years were devoted to the search of new strategies that could help to overcomethis problem. The rst important step forward was the nding of the proper relativisticexpression of the nuclear spin-rotation tensor (M), recently published by two groups.[2, 3]Then, the next step was to look for new relativistic Flygare-type relationships,[4] some ofthem will be shown in this presentation.The rst clues for these developments were built from the relationship among and Mwithin the two-component relativistic LRESC model. Besides, we had to introduce a fewother well dened assumptions: (i) relativistic corrections must be included in a way tobest reproduce the relationship among the (ee) term (called paramagnetic within the non-relativistic domain) of and its equivalent part of M, (ii) as happens in Flygares rule, theshielding of free atoms shall be included to improve accuracy and iii) one should includea Spin-dependence in the highest accurate model, through a new completely relativisticterm which generalize a previous Spin-orbit one.[5]We found that such a spin{dependent term isSY 􀀀 atom;SY, where SY = hh (r􀀀rY )jr􀀀rY j3 ; S(4) ii,being r 􀀀 rY the electron position with respect to the position of nucleus Y , and S(4) thefour-component total electron spin.In this presentation we shall show how can our best relativistic Flygare-type modelbe derived and also a new relativistic relationship that appears among the rotational g-tensor and the magnetic susceptibility tensor. Some applications to halogen containinglinear molecules will be shown, together with the fact that the dierence among the parallelcomponent of (Xe) in XeF2 and (Xe) of the free atom is almost completely describedby that new term.