The ORP basis set designed for optical rotation calculations

Details of generation of the optical rotation prediction (ORP) basis set developed for accurate optical rotation (OR) calculations are presented. Specific rotation calculations carried out at the density functional theory (DFT) level for model chiral methane molecule, fluorooxirane, methyloxirane, and dimethylmethylenecyclopropane reveal that the ORP set outperforms larger basis sets, among them the aug-cc-pVTZ basis set of Dunning (J. Chem. Phys. 1989, 90, 1007) and the aug-pc-2 basis set of Jensen (J. Chem. Phys. 2002, 117, 9234; J. Chem. Theory Comput. 2008, 4, 719). It is shown to be an attractive choice also in the case of larger systems, namely norbornanone, β-pinene, trans-pinane, and nopinone. The ORP basis set is further used in OR calculations for 24 other systems, and the results are compared to the aug-cc-pVDZ values. Whenever large discrepancies of results are observed, the ORP values are in an excellent agreement with the aug-cc-pVTZ results. The ORP basis set enables accurate specific rotation calculations at a reduced cost and thus can be recommended for routine DFT OR calculations, also for large and conformationally flexible molecules.