Functions for Augmenting Basis Sets

With the 6-3IG basis sets, Pople and co-workers recommended a set of polarization function exponents based on an examination of the optimal SCF values for a variety of molecules. In most instances, the energy loss that resulted from not using the optimal polarization exponent was small because 

10 6-3IG , average of optimal SCF values Optimal SCF values for Hz (Feller)  

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