Kinetic Energy Matrix Elements for a two-electron Atom with Extended Hylleraas-CI Wave Function

Some typical kinetic energy integrals which arise in the application of extended Hylleraas-configuration interaction (E-Hy-CI) function in the framework of Rayleigh-Ritz method of variation, have been evaluated analytically for two-electron atomic systems. Closed-form expressions for the corresponding integrals which occur in the application of Hylleraas-CI functions, have also been derived as special cases.