Relativistic relationships among response properties

IGNACIO AGUSTIN AUCAR; SERGIO S. GOMEZ; CLAUDIA G. GIRIBET; GUSTAVO A. AUCAR

Marburg

Congreso; Relativistic effects on heavy elements REHE XII; 2017

Comité organizador local e internacional

Some of the most influential articles showing the best way to obtain the experimental absolute scale of NMR magnetic shieldings, σ (non-measurables) from both accurate measurements and theoretical calculations, were published more than forty years ago by Ramsey 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 overcome this problem. The first important step forward was the finding of the proper relativistic expression 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 of them will be shown in this presentation.The first clues for these developments were built from the relationship among σ and M within the two-component relativistic LRESC model. Besides, few other well defined assumptions were introduced: (i) relativistic corrections must be included in a way to best reproduce the relationship among the (ee) term (called paramagnetic within the non-relativistic domain) of σ and its equivalent part of M, (ii) as happens in Flygares rule, the shielding of free atoms shall be included to improve accuracy and iii) one should include a Spin-dependence in the highest accurate model, through a new completely relativistic term which generalize a previous Spin-orbit one.[5]We found that such a highly spin-dependent term is ν Y S − ν Y atom,S , where ν Y S = Y )×α hh (r−r ; S (4) ii, being r − r Y the electron position with respect to the position of |r−r Y | 3 nucleus Y , and S (4) the four-component total electron spin.In this presentation we shall show how can our best relativistic Flygare-type model be derived and also a new leading-order relativistic relationship that appears among the rotational g-tensor and the magnetic susceptibility tensor. New insights about the electronic mechanisms that underlies to those response properties and some applications to halogencontaining linear molecules will be shown, together with the fact that the difference among the parallel component of σ(Xe) in XeF 2 and σ(Xe) of the free atom is almost completely accounted for by that new highly spin-dependent term.[1] N. F. Ramsey, Phys. Rev., 78, 699 (1950); W. H. Flygare, J. Chem. Phys., 41, 793 (1964).[2] I. A. Aucar, S. S. Gomez, M. Ruiz de Azúa and C. G. Giribet, J. Chem. Phys., 136,204119 (2012).[3] Y. Xiao and W. Liu, J. Chem. Phys., 138, 134104 (2013).[4] I. A. Aucar, S. S. Gomez, C. G. Giribet and G. A. Aucar, Phys. Chem. Chem. Phys.,18, 23572 (2016).[5] I. A. Aucar, S. S. Gomez, C. G. Giribet and G. A. Aucar, J. Phys. Chem. Lett., 7,5188 (2016).