Parity violation effects on the electric field gradient.

The parity violation (PV) effects on the electric field gradient (EFG) and the nuclear quadrupole coupling constant (NQCC) of a wide variety of chiral systems are studied in a four-component (4c) framework. Formal expressions and calculations of the PV effects on the EFG are presented for the first time at 4c Dirac Hartree-Fock level. The chiral systems studied are XHFClY (X = C, Sn; Y = Br, I, At) molecules together with NUHXY (X, Y = F, Cl, Br, I) and NUF XY (X, Y = Cl, Br, I) uranium containing systems. We found that for the latter, calculations of PV effects on NQCC are two orders of magnitude lower than the current experimental precision and they are suitable candidates for future PV measurements in NQCC, in particular the NUHFCl chiral molecule. The dependence on the basis set, the nuclear charge distribution model and the kinetic balance prescription related to the negative-energy states is also analysed.