Guseinov, Israfil Isa2025-01-272025-01-2720070259-97911572-8897https://doi.org/10.1007/s10910-006-9111-zhttps://hdl.handle.net/20.500.12428/26664Using complete orthonormal sets of Psi(alpha)-exponential type orbitals (Psi(alpha)-ETOs, alpha =1, 0, -1, -2, ...) introduced by the author, the series expansion formulae are derived for the two-center integer and noninteger n STO (ISTO and NISTO) charge densities in terms of integer n STOs at a third center. The expansion coefficients occurring in these relations are presented through the two-center overlap integrals between STOs with integer and noninteger principal quantum numbers. The general formulae obtained for the STO charge densities are utilized for the evaluation of two-center Coulomb and hybrid integrals of NISTOs appearing in the Hartee-Fock-Roothaan approximation. The final results are expressed in terms of both the overlap integrals and the one-center basic integrals over integer n STOs. It should be noted that the result for the multi-center multielectron integrals with two-center noninteger n STO charge densities presented in this paper were not appeared in our past publications.eninfo:eu-repo/semantics/closedAccessSlater type orbitalsnoninteger principal quantum numberscharge densitiesmulti-center integralsArticle42341542210.1007/s10910-006-9111-zQ2WOS:0002492129000122-s2.0-34548462118Q2