Relativistic unitary coupled-cluster study of the electric quadrupole moment and magnetic dipole hyperfine constants of 199Hg+

Searching for an accurate optical clock which can serve as a better time standard than the present-day atomic clock is highly demanding from several areas of science and technology. Several attempts have been made to build more accurate clocks with different ion species. In this paper, we discuss the electric quadrupole and hyperfine shifts in the 5d96s22D5/2(F=0,mF=0)↔5d106s 2S1/2(F=2,mF=0) clock transition in 199Hg+, one of the most promising candidates for next-generation optical clocks. We have applied Fock-space unitary coupled-cluster theory to study the electric quadrupole moment of the 5d96s22D5/2 state and magnetic dipole hyperfine constants of 5d96s22D3/2,5/2 and 5d106s12S1/2 states, respectively, of 199Hg+. We have also compared our results with available data. To the best of our knowledge, this is the first time a variant of coupled-cluster theories has been applied to study these kinds of properties of Hg+ and is the most accurate estimate of these quantities to date