Addition theorem of Slater-type orbitals: Application to H-2(+) in a strong magnetic field

The C-matrix representation of the two-range addition theorem of Slater-typ e functions (STFs) proved to be very useful especially when using a compute r algebra system. However, for intensive numerical work it was found advant ageous to use the G- (or T-) matrix representation for the apart of STFs wh ile the remaining term is expanded with the help of the addition theorem of solid spherical harmonics. Two major advantages are to be related to this procedure. On the one hand, the new C matrices are symmetric and most impor tant can be generated recursively. On the other hand, this procedure allows one to generalize and to unify the previous E-and F-matrix expansions. Ind eed, the new T-matrix form allows one to avoid the calculation-of C-matrix elements and much more important to use a recursive scheme in order to gene rate their elements. As an application of these formulas, we address in the last part of this work the study of the electronic structure of H2+ when s ubjected to a strong magnetic field. Our calculation shows that the expansi on in terms of spherical harmonics (i.e., STFs) becomes slowly convergent f or large values of the magnetic field.