Basis set superposition error is inherent to quantum mechanical calculations. First explored through intermolecular complexes, it was later demonstrated to have intramolecular effects as well. To correct for both of these errors, the counterpoise correction is used. For the standard intermolecular correction, each molecule is considered as a fragment. To extend the correction for intramolecular error, each molecule is split into several fragments, all used in the correction. The major difference between each correction resides in the size of the fragments and in their selection; some fragments can (or should) be omitted. We have systematically tested three methods against several systems with experimentally known enthalpy of reaction, using Dunning-Hay and 6-31G basis sets. Energy calculations results have shown deviations from experimental values ranging from 36 to 21% without corrections, compared to 26 to 9.5% with the corrections.

Assessment of correction methods for intramolecular basis set superposition error

245th National Meeting (2013)

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