Search

In natural processes involving weak interactions, a violation of spatial parity conservation should appear. Its effects are expected to be observable in molecules using different spectroscopic methodologies, but due to the tiny magnitude of these effects they have never been measured yet. We present a theoretical analysis of four-component relativistic nuclear-spin-dependent parity-violating nuclear spin-rotation and NMR shielding tensors in a set of tetrahedral chiral molecules. This work highlights the crucial role played by the ligands and the electronic structure of the chiral center in the enhancement of these effects, leading the way towards targeted design of promising molecules for measurements.

It is known that the nuclear-spin-dependent parity-violating contributions to the NMR shielding and the nuclear spin-rotation tensors (${\bf \sigma}^{PV}$ and ${\bf M}^{PV}$, respectively) are formally related each other within the non-relativistic (NR) regime. Such a formal relationship is not any longer valid within the relativistic domain. A new more general formal relationship, that is valid within the relativistic framework is shown here, being developed through the use of the LRESC model. The formalism of polarization propagators is applied to write the different contributions to both properties within both regimes, relativistic and NR. In the relativistic regime the Dirac-Coulomb Hamiltonian was selected as the unperturbed Hamiltonian. Theoretical developments together with results of calculations performed on the H$_2X_2$ series of molecules ($X =$ $^{17}$O, $^{33}$S, $^{77}$Se, $^{125}$Te and $^{209}$Po) show that also within the relativistic regime there is a close relationship between the parity-violation contributions to both properties. In particular, spin-dependent contributions are the most important in the four-component calculations of electroweak effects on the isotropic values of both tensors, ${\bf \sigma}^{PV}$ and ${\bf M}^{PV}$, being also responsible for the breakdown of the previously mentioned NR relationship among them. This last relationship is still fulfilled when the scalar-relativistic effects are considered., Comment: 17 pages, 16 figures

DIRAC is a freely distributed general-purpose program system for 1-, 2- and 4-component relativistic molecular calculations at the level of Hartree--Fock, Kohn--Sham (including range-separated theory), multiconfigurational self-consistent-field, multireference configuration interaction, coupled cluster and electron propagator theory. At the self-consistent-field level a highly original scheme, based on quaternion algebra, is implemented for the treatment of both spatial and time reversal symmetry. DIRAC features a very general module for the calculation of molecular properties that to a large extent may be defined by the user and further analyzed through a powerful visualization module. It allows the inclusion of environmental effects through three different classes of increasingly sophisticated embedding approaches: the implicit solvation polarizable continuum model, the explicit polarizable embedding, and frozen density embedding models. DIRAC was one of the earliest codes for relativistic molecular calculations and remains a reference in its field., Comment: The following article has been submitted to The Journal of Chemical Physics. After it is published, it will be found at https://aip.scitation.org/toc/jcp/current