Accuracy of expectation values of one-electron operators obtained from Hartree-Fock wavefunctions expanded using Lambda functions

The accuracy of the expectation values ( < A > ) of one-electron operators is examined using Hartree-Fock wavefunctions expanded using ? functions. In this expansion, 150 terms, then 149, 148, and 147 terms are used for the s-, p-, d-, and f-symmetries, respectively. The systems investigated are He-Ne and the Group 18 atoms of Ar-Og. The one-electron properties investigated are the cusp condition (CC), the electron density at the nucleus (?(0)), and < r(i) > (i =-2,..., 9). Convergence of < A > is examined by increasing the number of expansion terms (N) up to the given limit (150). The number of significant figures (SF) of < A > is counted by comparing the calculated value at N=150 ( < A(150) > ) with the extrapolated value < A(8) > . For He, the SF of CC is found to be 26. For the atoms under consideration, the SF of CC is approximately half that of the total energy (TE). The SFs of expectation values of the other properties are also smaller than for the TE.