Investigation of the quality of standard sulfur basis sets for molecules using a new generator coordinate method approach: Application to 2,2′‐bithiophene

Abstract

AbstractIn this work we have applied the generator coordinate method (GCM) to analyze the quality of the standard 6‐311G** and 6‐311++G** Pople's basis sets for the sulfur atom at the Hartree–Fock level of theory. When using the GCM theory, it is necessary to uncontract the basis set to obtain information about the quality of the basis set. To study large molecules such as bithiophene, for which it is difficult to use uncontracted basis sets at the ab initio level, we have developed a technique that makes possible the use of contracted basis sets within the GCM theory. To test such an approach, we have studied small molecules containing the sulfur atom, such as H2S and SCl2. The results show the suitability of using contracted basis sets for these systems with the GCM theory. In the study of contracted basis sets for the bithiophene molecule, we proposed and tested a modified basis set containing additional diffuse functions on the sulfur atom in the light of the GCM approach. The current study enables for the first time the assessment of the quality of atomic basis sets inside a molecular environment. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 95: 194–204, 2003