Electron-Correlated Calculations of Electric Properties of Nucleic Acid Bases

Abstract

Full geometry optimizations have been performed at the MP2 level of theory using the 6-31G(d,p) basis set for the five common nucleic acid bases (uracil, thymine, cytosine, adenine, and guanine) and three related bases (fluorouracil, 5-methylcytosine, and hypoxanthine). Several electric properties were subsequently calculated using the optimized geometries and the larger polarized basis sets of Sadlej. Including electron correlation decreases the magnitude of the dipole moments by 10−15% for every base except adenine. In all cases, inclusion of electron correlation increases the mean polarizability by 8−12% and also increases the polarizability anisotropy by as much as 14−20%. Results for structurally similar bases were compared in order to qualitatively study the effects of functional group substitution on geometries and electric properties.