High Angular Momentum Basis Sets

Ah initio methods can yield reliable, quantitatively correct results. It is important to use basis sets with diffrise functions and high-angular-momentum polarization functions. Hyperpolarizabilities seem to be relatively insensitive to the core electron description. Good agreement has been obtained between ECP basis sets and all electron basis sets. DFT methods have not yet been used widely enough to make generalizations about their accuracy. 

A prime advantage of the perturbational approach is that the individual terms are evaluated explicitly, rather than as the difference between very much larger quantities as is true of supermolecule approaches. These SAPT terms are free of basis set superposition error. More important, each term corresponds to a well-defined physical phenomenon, which permits an insightful analysis. Each term can be evaluated using a different basis set, most appropriate for that particular component. For example, dispersion requires orbitals of high angular momentum whereas electrostatics can usually be derived with only a moderate basis set. 

Perhaps the most interesting aspect of the analysis which led to the development of the correlation consistent basis sets is the fact that high angular momentum functions are necessary for achieving liigh accuracy. While d-polarization functions are sufficient for a... 

For most semiempirical MO methods or uncorrelated ab initio methods, the demand for basis sets is drastically increased, while the accuracy is usually reduced when going from light- to heavy-element systems. However, as we will show, the gradient-corrected DFT methods seem to have smaller basis set truncation error, so they are quite reliable for systems as heavy as those of actinides, and the results seem, at least qualitatively, to be less dependent on the choice of basis sets with high-angular-momentum components (40). 

High angular momentum basis sets augmented with diffuse functions represent the most sophisticated basis sets available. Basis sets with multiple polarization functions include ... 

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