Atoms in strong external fields polarizabilities

The generalized Sturmian method is particularly well suited for calculating the spectra of few-electron atoms in strong external fields. In the case of a uniform electric field, the additional term in the potential (in atomic units) is 

Having constructed the matrices and T , we are in a position to calculate the spectra of an isoelectronic series of atoms and ions for all values of the nuclear charge Z, and for all values of the external electric field. We first choose a value of Z. Then, for many values of 17 we solve the secular equation (46). Finally, making use of the relationship 17 = /pl, we are able to plot atomic spectra, induced dipole moments, induced transition dipole 

From equations (6) and (51) we can see that the dipole moment of the state P l will be given by 

Since the ground states of atoms and ions have no intrinsic dipole moment, their polarizabilities are given by 

It is also possible to calculate field-induced transition dipole moments. When Pk Pk i the field-induced transition dipole moment between two states is given approximately by 

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