AbSbCtSApproximate numerical linear dependence among the columns of the two-electron integral matrix and the positiveness of the Coulomb operator are exploited in order to reduce the number of integrals that need to be calculated when a numerical accuracy is given by the machine in use or by the choice of the investigator. Numerical results presented indicate that the method leads to an algorithm for carrying out the two-electron integral four-index transformation which in practice can be achieved in a small fraction (-4-$) of the time required to generate the integrals by one of the fastest available Gaussian integral programs, Almlof's MOLECULE. This effectively removes one of the major bottlenecks of computational quantum chemistry.La dtpendance lintaire numtrique approximative entre les colonnes de la matrice formke des inttgrales B deux tlectrons et la positivitt de I'opirateur de Coulomb ont t t e exploittes pour rtduire le nombre d'inttgrales a calculer pour une prtcision numtrique donnte par I'ordinateur ou par le choix du chercheur. On prtsente des rtsultats numkriques, qui indiquent que notre mtthode mtne a un algorithme pour la transformation a quatre indices des intkgrales a deux tlectrons, qui ne requiert qu'une petite fraction (-$-$) du temps nkcessaire pour gkntrer les mbmes intkgrales par un des programmes pour des orbitales gaussiennes les plus rapides, le MOLECULE de Almlof. Ceci enlttve d'une facon efficace une des difficultts principales des calculs de la chimie quantique.Die approximative numerische lineare Abhangigkeit zwischen den Spalten der von Zweielektronenintegralen gebildeten Matrix und die Positivitat des Coulomboperators werden ausgenutzt urn die Anzahl der Integrale zu reduzieren, die fur eine von der Rechenmaschine oder dem Forscher gegebene Genauigkeit gebraucht werden. Die vorgelegenen numerischen Ergebnisse zeigen, dass die Methode zu einem Algorithmus fur die Vierindextransformation der Zweielektronenintegrale fuhrt, der in der Praxis ausgefuhrt werden kann in einem Bruchteil (-4-4) der &it, die mit einem der schnellsten gausschen Integralprogramme, dem Almlof'schen MOLECULE, fur die Erzeugung der Integrale gebraucht wird. Dadurch wird eine der wichtigsten Schwierigkeiten in quantenchemischen Berechnungen beseitigt.

Minimal basis full valence CI calculations of potential curves are reported for more than 300 low-lying states of O2, O+2, and O2+2. A large number of new bound states of O+2 and some metastable states of O2+2 are predicted, and from a comparison with known states of O2 and O+2, predictions are made for the spectroscopic constants of the as yet experimentally unknown states.

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The hyperfine structure constants in the lowest 4 P o and 4 P e states of the isoelectronic sequence Li-F 6+ have been calculated from Hartree-Fock and accurate configuration interaction (CI) wavefunctions, in good agreement with available experimental results for Li. In addition, Hartree-Fock calculations of energies and hfs constants for several higher 4 S, 4 P o, 4 D and 4 D o states of Li are reported.

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