How relevant is the relativistic effect on the calculation of coupling constant polarizability of a molecule.

STEPHAN P. A. SAUER; MARTA B. FERRARO; GABRIEL I. PAGOLA

Ciudad de Buenos Aires

Conferencia; MESBA 2016 Molecular Electronic Structure; 2016

Nuclear magnetic resonance spectrometers presently available are unable to recognize the two mirror-image forms of a chiral molecule, because, in the absence of a chiral solvent, the NMR spectral parameters (chemical shifts and spin-spin coupling constants) are identical for the two enantiomers. Chirality may nevertheless, at least in theory, be recognized in liquid-state NMR spectroscopy by applying strong electric fields and measuring a pseudoscalar contribution to nuclear spin-spin coupling polarizability[1]. The components of the coupling polarizability are derivatives of the nuclear magnetic resonance (NMR) indirect nuclear spin?spin coupling with respect to an external electric field[2]. In this study, we present the calculations of the coupling constant polarizability of a molecule at fully relativistic level using Dirac code and are compared with no-relativistic calculations using Dalton [4] code. Both sets of calculations have been made at the level of density functional theory for the small chiral molecules X2H2 with X=O, S, Se, Te , which allowed us to perform calculations with the largest available basis sets optimized for the calculation of NMR coupling constants. We found that the difference between the relativistic and no-relativistic level are small for systems with X=O or S but get close to 20% for the molecule with X= Se and close to 50% for the molecule with X=Te.References[1] G. I. Pagola, M. B. Ferraro, S. Pelloni, P. Lazzeretti, S. P. A. Sauer, Theoretical Chemistry Accounts, 129, pp. 359-366, (2011) [2] H. Kjær, M.R. Nielsen, G.I. Pagola, M.B. Ferraro, P. Lazzeretti, S.P.A. Sauer, Journal of Computational Chemistry 33, pp. 1845-1853, (2012)[3] DIRAC: Program for Atomic and Molecular Direct Iterative Relativistic All-electron Calculations, Release 14.0, http://daltonprogram.org[4] DALTON, A Molecular Electronic Structure Program, Release Dalton2011.