Calculations Of Dynamic Multipolar Polarizabilities Of Cd Atom

With the rapid development of laser cooling and trapping techniques,the precision of atomic clocks has been greatly improved.The best Sr optical lattice clock at this stage has reached a precision of 10-18.In the fields of determining fundamental phys-ical constants,testing Lorentz invariance,and searching for new physics,the related experiments have higher demands on the precision of atomic clocks.The development of higher precision atomic clocks requires precise control on the interaction of the opti-cal clock atoms with the external field and the reduction of the uncertainty of the system.The Cd atom has been proposed as a new candidate for the development of a lattice clock because of its smaller blackbody radiation shift at room temperature.The leading term of the Stark frequency shift is eliminated when the magic wavelength of Cd atoms is experimentally determined At the same time,the importance of multipole and higher-order Stark shifts emerges,which needs to be quantitatively evaluated.The combined method of the Dirac-Fock plus core polarization(DFCP)and relativistic configuration interaction has been widely applied to the calculation of the structural properties of heavy atoms and plays an important role in predicting the properties of heavy atoms quantitatively and qualitatively.The DFCP method only includes the leading term of the interaction between core-electrons and valence-electron and ignores the high-order core polarization potential.With the increase of nuclear charge and the high demand for precision,the influence of high-order core-polarization potential on the atomic structure properties needs to be quantitatively analyzed.In this thesis,the atomic orbitals and ground state energies of closed-shell atomic systems are calculated by Hartree-Fock and Dirac-Fock methods based on B-spline ba-sis set.The dynamic polarizabilities of the Cd clock states are studied by an improved combined method of the Dirac-Fock plus core polarization and relativistic configuration interaction methods.The effects of the high-order core polarization potentials on po-larizabilities of the optical clock atoms Cd,Mg,and Sr have been evaluated.The main contents of this thesis are:(1)The Hartree-Fock and Dirac-Fock method based on the B-spline basis set are developed to calculate the ground state energies of the closed-shell atomic systems,and the convergence tests are also performed.Comparing the result with other theoretical methods,the correctness and reliability of the program are verified,which lays the foun-dation for the calculation of the core for two-valence-electron atomic systems.(2)The higher-order core polarization potential is considered in the relativistic core polarization potential combined relativistic configuration interaction method.The reduced matrix elements and static dipole polarizability of Mg and Sr atoms are calcu-lated.Detailed comparisons are made with the results without considering the higher-order core polarization potential,and the effect of high-order core polarization potential on the polarizabilities of Mg and Sr optical lattice clocks are evaluated.(3)The static polarizabilities of Cd atom for different core polarization potentials are calculated.The effect of higher-order core polarization potentials on energy,reduced matrix elements,and multipolar polarizabilities are evaluated in detail.It is found that the high-order core-polarization potential has much larger effects on the excited states.The detailed comparisons with available literature demonstrate that taking account of the high-order core-polarization potentials is a simple and effective approach to improve atomic properties for heavy atoms.And this method can be extended for the calculations of non-S state of heavier and complex atomic systems.