Ab initio calculation of electric properties for the BH, CO, CS and N2 molecules

In the present paper, improved basis set are proposed for calculating electric properties of some diatomic molecules. The methodology employed used standard basis set as reference and new extrabasis are added on atoms in molecules using experimental and theoretical dipole moment, polarizability, first and second hyperpolarizabilities as reference data. In general, the final basis set were smaller than those described in the literature for calculating such sensitive properties. The results at CCSD(T) level were in best agreement with reference experimental data, with average error of only 3% considering all molecules. However, we also found satisfactory results when the less expansive MP2 level is used with the new basis sets, especially for polarizability and hyperpolarizabilities. The average error taking properties from all molecules was only 6% at MP2 level of theory. Thus, this low cost level in conjunction with the basis sets proposed here might be a suitable level for calculation of electric properties for larger molecules, where CC is prohibitive.