Theoretical aids in screening candidates for atomic clocks: Illustration for Yb II

Abstract

Highly accurate electronic-structure calculations for metastable electronic excited states are needed to supplement scant experimental data in screening possible systems for new higher-precision atomic clocks. We test the suitability of relativistic coupled-cluster methods for the low-lying F-2 degrees excited states of the Yb II ion by computing the ionization potentials (IP) for the S-2(1/2) and F-2 degrees states of Yb I and the [Xe]4f(14)6s (S-2(1/2)) -> [Xe]4f(13)6s(2) (F-2 degrees(j)), j = 5/2, 7/2, electric octupole transition amplitudes. The calculations establish a minimum lifetime of six years and of 10(-1) s for the F-2 degrees(7/2) and F-2 degrees(5/2) states, respectively. In addition, computations for the lifetimes (T) of its [Xe]4f(14)6p (P-2 degrees) states are compared with high-precision experimental data as tests of the accuracy of our predictions. To our knowledge, this is the first relativistic ab initio estimate of the lifetime and ionization potential for the F-2 degrees states of Yb II, and the results demonstrate the suitability of these methods to aid in screening other candidates for atomic clocks.