Single-center expansions, maximum

These single-center expansions must be truncated at some suitable maximum value. These maximum values, the step sizes on the grid. 

When the size of the nuclear framework of the molecule or cluster is small compared to the extent of the diffuse basis functions, it probably does not matter much where the floating center is positioned. In applications to (H20) , for example, Sommerfeld et al. place a single set of diffuse functions on one oxygen atom, using an even-tempered progression out to a maximum FWHM of 80 A. It is reported that the VDE depends only weakly on which oxygen atom is chosen as the center of this expansion. 

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