Parity violation energies of C₄H₄X₂ molecules for X = O, S, Se, Te and Po^†

1. Paper dedicated to Professor Werner Kutzelnigg on the occasion of his 80^th birthday.

Abstract

Parity-violating contributions, with the same magnitude but opposite sign, to the energies of 1,2 enantiomers of dioxin, dithiin, diselenin, ditellurin and dipolonin have been calculated. Theoretical predictions, which can be classified among the largest reported so far, indicate that the P enantiomer is energetically more stable than M. As expected, parity-violating effects increase with the first power of the neutron number and the fourth power of the atomic number for X = O, S, Se, Te and Po. The trend predicted by Laerdahl and Schwerdtfeger [Phys. Rev. A 60, 4439 (1999)] and by Berger [J. Chem. Phys. 129, 154105 (2008)] for H₂X₂ molecules, characterised by free rotation about the X–X internuclear axis, is therefore confirmed for the series of more rigid C₄H₄X₂ compounds, in which limited deformations can take place.

Keywords:

• parity violation in molecules
• non-relativistic and relativistic calculations
• molecular geometry effects in six-membered cyclic systems

Acknowledgements

The authors would like to thank one of the reviewers for the insight and suggestions contained in his/her first reply. Financial support from the Italian MIUR (Ministero dell’Istruzione, dell’Università e della Ricerca) via the PRIN 2009 scheme is gratefully acknowledged.

Notes

^aThe conversion factor from atomic units to SI units from the CODATA recommended values [53] is E _h =4.35974417× 10⁻¹⁸ J.

^bDihedral angle between the planes C₁X₁X₂ and X₁X₂C₂, in degrees.

^cScaled using the method of Bouchiat and Bouchiat [51], and the K _r values 1.031, 1.114, 1.533, 2.533, 9.893 for O down to Po, from table I of Berger [72].

1. Paper dedicated to Professor Werner Kutzelnigg on the occasion of his 80^th birthday.