Effect of Basis Set Size on the Quality of the Molecular Electrostatic Potential

Faculty #17
Discipline: Chemistry and Chemical Sciences
Subcategory: STEM Research

Kevin E. Riley - Xavier University of Louisiana
Co-Author(s): Khanh-An Tran

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The electrostatic potential is a very useful molecular property that can be used to predict such things as chemical reactivity and participation in noncovalent interactions. The electrostatic potential can be determined experimentally, but is much more commonly obtained using computational chemistry techniques. Most often medium basis sets, such as 6-31G* are used to compute this property, but sometimes smaller basis sets, such as STO-3G and 3-21G, are used. To date, studies seeking to clarify the role that the basis set plays in the quality of the electrostatic potential have not been carried out. Here we generate electrostatic potentials for three molecules, HCN, BrCN, and H3CCH, using a large number of basis sets, ranging in size from STO-3G to aug-cc-pVTZ, along with the Hartree-Fock and DFT (B3LYP and M06-2X) methods. It is found that basis sets at least as large as 3-21G* must be used in order to consistently generate reasonably accurate electrostatic potentials.

Funder Acknowledgement(s): NSF HBCU UP

Faculty Advisor: None Listed,