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Some typical overlap/potential energy integrals which occur in the use ofextended Hylleraas-configuration interaction (E-Hy-CI) functions withSlater-type orbital (STO) basis for two-electron atomic structure calculations,have been evaluated analytically. The corresponding kinetic energy integralshave been simplified first by using formulas derived from Gauss' divergencetheorem in vector calculus, and then expressed in terms of overlap / potentialenergy matrix elements. Also closed-form expressions for such integrals whicharise in the application of Hylleraas-CI functions, and CI functions have beenobtained as special cases, and the calculated values are found to agree wellwith correct results published by other investigators.

Analytic Evaluation of two-electron Atomic Integrals involving Extended Hylleraas-CI functions with STO basis