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>Effective convergence to complete orbital bases and to the atomic Hartreendash;Fock limit through systematic sequences of Gaussian primitives
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Effective convergence to complete orbital bases and to the atomic Hartreendash;Fock limit through systematic sequences of Gaussian primitives
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机译：Effective convergence to complete orbital bases and to the atomic Hartreendash;Fock limit through systematic sequences of Gaussian primitives
Optimal starting points for expanding molecular orbitals in terms of atomic orbitals are the selfhyphen;consistenthyphen;field orbitals of the free atoms and accurate information about the latter is essential for the construction of effective AO bases for molecular calculations. For expansions of atomic SCF orbitals in terms of Gaussian primitives, which are of particular interest for applications in polyatomic quantum chemistry, previous information has been limited in accuracy. In the present investigation a simple procedure is given for finding expansions of atomic selfhyphen;consistenthyphen;field orbitals in terms of Gaussian primitivestoarbitrarilyhighaccuracy. The method furthermore opens the first avenue so far for approachingcompletebasissetsthroughsystematicsequencesofatomicorbitals. It is shown that, for expansions of atomic SCF orbitals in terms ofevenhyphen;temperedGaussian primitives, the energyhyphen; optimized exponents aresimpleanalyticfunctionsofthenumberofprimitivesusedintheexpansions.With the help of these formulas, accurate atomic SCF calculations in terms ofverylarge sets of primitives can be carried out without exponent optimization and the energies from such calculations converge to the Hartreendash;Fock limit on smooth curves. It proves possible toextrapolatetothelimitandtogiveestimatesfortheerrorboundsoftheextrapolation. Quantitative data are given for all atoms in the first three periods of the periodic system. The Hartreendash;Fock limits obtained in this manner are equal or superior to previous calculations based on numerical methods or on expansions in terms of exponential type primitives. From the given atomic SCF orbitals, extended basis sets for molecular calculations are easily obtained by Raffenettirsquo;s method.
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