Understanding the Physics behind NMR Spectroscopic Parameters from Polarization Propagators

GUSTAVO A. AUCAR

Anglet

Congreso; CHITEL 2010 36 edición; 2010

Comité organizador perteneciente a l’Université de Pau et des Pays

         NMR spectroscopic parameters, J and σ, were first defined and extensively studied within the non-relativistic, NR, framework. Whence they were found to strongly depend on relativistic effects several new formalisms were developed and few are still under development1 in order to include such effects.  Polarization propagators were first presented in the early 1970s by Jens Oddershede and coauthors. They are special devices from which one can get a deep understanding of the electronic mechanism which produce any response property like NMR spectroscopic parameters. For these properties one gets reliable results when including electronic correlation, though when the system is a heavy-atom containing molecule one is also forced to add relativistic effects. Since the early 1990s we have been involved in its relativistic and QED extensions2. In this presentation we are going to show how all three levels of theory: NR, relativistic and QED can be treated coherently within polarization propagators3.  Some of the most subtle properties of J and σ will be explained in a simple and powerful way: the sign of J, Karplus rule, relativistic effects, and diamagnetic and paramagnetic contributions. Several rules which are valid within the NR regime are broken when including relativity in a proper way. It will be stressed that the whole set of electronic mechanisms that appears within the NR regime and also within its quasi-relativistic extensions are now completely unified.               References 1.   P. Pyykko, Chem. Phys. 22, 289-294 (1977). E. van Lenthe et al. J. Chem. Phys. 99, 4597-4603 (1993); H. Nakatsuji et al., Chem. Phys. Lett. 233, 95-99 (1995); G. A. Aucar et al. J. Chem. Phys. 110, 6208-6217 (1999); J. I. Melo et al. J. Chem. Phys. 118, 471-482 (2003); J. Vaara, Phys. Chem. Chem. Phys. 9, 5399-5418 (2007); M. Rapisky et al., Chem. Phys. 356, 236-246 (2009); L. Cheng et al. J. Chem. Phys. 131, 244113-244119 (2009); S. Hamaya and H. Fukui, Bull. Chem. Soc. Jpn. 83, 635-642 (2010). 2.   G. A. Aucar and J. Oddershede, Int. J. Quantum Chem. 47, 425-432 (1993); R. H. Romero and G. A. Aucar, Phys. Rev. A 65, 53411-53420 (2002). 3.   G. A. Aucar, R. H. Romero and A. F. Maldonado, Int. Rev. Phys. Chem. 83, 1-64 (2010).