Theoretical Study On Static Electric-dipole Polarizability Of Complex Atoms

When atoms are in the external electric field,the deviation of the electron cloud from the normal distribution is described as the polarizability.It plays an important role in many fields,such as atomic parity non-conservation,atomic optical clock,quantum computation,long-range interatomic potentials and Bose-Einstein condensate.The polarizabilities for the atoms with single-or double-valence electrons(group IA and group IIA)have been widely studied using many-body perturbation theory,relativistic coupled-cluster theory,etc.However,for complex atoms with multiple-valence electrons,it is very difficult to consider the effects of electron correlation.Therefore,it is necessary to develop a set of program for calculating the polarizability of complex atoms.The fully relativistic multi-configuration Dirac-Hartree-Fock(MCDHF)method is a very good method to calculate the atomic parameters with multi-valence electron atoms.The GRASP package based on this method is also a very powerful software,which has a very wide range of applications in the calculations of structural parameters,such as fine structure constant,isotope shift and transition probability.Therefore,we have developed a set of program to calculate the polarizabilities of complex atoms based on this method and combined with GRASP2018 package.Firstly,the transition energies,electric-dipole transition matrix elements and electric-dipole static polarizabilites of He atoms are calculated.The present results are in good agreement with other theoretical and experimental results,which verify the reliability and accuracy of our new program.Be atoms have important applications in fine structure constants,quantum computations and isotope shifts.The 2s2p ³P₀?2s^{2 1}S₀forbidden transition is also widely used in the precis measurement experiments.Therefore,we use this new program to calculate the energy eigenvalues,transition energies electric-dipole transition matrix elements,static electric-dipole polarizabilities of 2s2p ³P₀and 2s^{2 1}S₀states and the corresponding blackbody radiation shift of Be atoms.Through the analysis,it is found that the present results are in good agreement with the results of other theoretical calculations and experimental measurements.Because the polarizabilities of the two clock transition states of Be atoms are very close,the BBR shift of Be atoms is one to two orders of magnitude smaller than that of other alkali earth metal atoms,which is of great significance to the study on the precis measurements of Be atoms.Xe atoms is the typical antimagnetic atoms with strong CP-violation,which make Xe atoms a candidate element for the experiment of atomic permanent electric dipole moment.Therefore,we calculate the energy levels,transition energies,electric-dipole transition matrix elements and electric-dipole polarizabilities of Xe atoms.We found that the configuration interactions and electron correlation effects for Xe atoms are very complex.When the inner-shells are opened,the polarizabilities change greatly,which further indicate that the transitions among the inner-shells of the complex atoms contribute greatly to the polarizabilities,which cannot be ignored in the calculated process.