Closed formulae for (1s|1s), Slater two‐center integrals, using the three‐center nuclear attraction integral program in spherical coordinates

The strategy of using expansions in spherical harmonics of displaced Slater‐type (exp (−α x ) ) orbitals to evaluate multicenter molecular integrals is applied to three‐centered nuclear attraction integrals (potential due to the product of separated Slater‐type orbitals). Closed formulae are produced for nine terms of an infinite series for interior region, (inside − ipot) r 2 < a , and 14 terms for Exterior Region, (outside − epot) r 2 > a . The value a = 2 is chosen for the interior region and r = 14 for the exterior region. Our focus is to obtain a closed formula for the Slater formula. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004