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

Rajat K. Chaudhuri^1a, Karl F. Freed^2b, Sudip Chattopadhyay^3c and Uttam Sinha Mahapatra^4d

¹ Indian Institute of Astrophysics - Bangalore-560034, India
² The James Franck Institute, University of Chicago - Chicago, Il 60637, USA
³ Department of Chemistry, Bengal Engineering and Science University - Shibpur, Howrah 711103, India
⁴ Department of Physics, Maulana Azad College - 8 Rafi Ahmed Kidwai Road, Kolkata-700013, India

^a rkchaudh@iiap.res.in
^b freed@uchicago.edu
^c sudip_chattopadhyay@rediffmail.com
^d uttam.mahapatra@linuxmail.org

Received: 14 February 2012
Accepted: 27 March 2012

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 ²F^o excited states of the Yb II ion by computing the ionization potentials (IP) for the ²S_1/2 and ²F^o states of Yb I and the , 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 ²F^o_7/2 and ²F^o_5/2 states, respectively. In addition, computations for the lifetimes (τ) of its [Xe]4f¹⁴6p(²P^o) 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 ²F^o states of Yb II, and the results demonstrate the suitability of these methods to aid in screening other candidates for atomic clocks.