Momentum space properties of two-electron atoms

A series of increasingly accurate wavefunctions for H - , and He built from Gaussian geminals is presented. Such wavefunctions are found to be much more compact than configuration interaction wavefunctions of similar accuracy. Moreover, comparison with nearly exact values shows that they predict one- and two-electron moments in position space quite well but perform less satisfactorily with respect to point properties. The wavefunctions can be Fourier-Dirac transformed in closed form and are used to predict values of one- and two-electron momentum space properties including Compton profiles. Most of these momentum properties are expected to be of benchmark quality.