In Search of the Electron Electric Dipole Moment: Relativistic Correlation Calculations of the P,T-Violating Effect in the Ground State of HI+

We report the first results of ab initio relativistic correlation calculation of the effective electric field on the electron, Eeff, in the ground state of the HI+ cation. This value is required for interpretation of the suggested experiment on the search for the electron electric dipole moment. The generalized relativistic effective core potential, Fock-space relativistic coupled cluster with single and double cluster amplitudes (RCC-SD), and spin-orbit direct configuration interaction (SODCI) methods are used, followed by nonvariational one-center restoration of the four-component wave function in the iodine core. The RCC-SD value is Eeff=0.345x1024 Hz/e cm and SODCI study gives Eeff=0.336x1024 Hz/e cm (our final value). The structure of chemical bonding in HI+ is clarified, and a significant deviation of our value from that of Ravaine et al. [Phys. Rev. Lett. 94, 013001 (2005)] is explained