Precision calculation of the light shiftin optical frequency standards

The light frequency shifts induced by an external laser field are calculated for the spin-forbidden ³P_J–¹S₀ transitions in Mg, Sr, and Yb atoms. The calculations are performed within the framework of the perturbation theory using experimentally measured transition energies. The calculations of the higher-order dynamic Stark effect were initiated by precision measurements of trapped and cooled atoms as well as by the development of a highly stable optical atomic clock. The dispersion properties of the polarisability and hyperpolarisability components are analysed in the vicinity of resonances and so-called cross points for the ground and excited atomic levels. The radial matrix elements were calculated by the Green function method for the model potential.