Ab initio molecular orbital calculations of the static polarizabilities of xanthone analogues

The static polarizabilities, α, of various xanthone analogues (1–19) were estimated by ab initio molecular orbital calculations using the coupled perturbed Hartree-Fock (CPHF) method. The influence of basis sets on the calculated values was examined in detail and the reliability of the ECP approach was confirmed. A good linear relationship was found between the Δα values calculated using the 3–21G basis set and those using larger basis sets. The introduction of substituents generally increases 〈α〉, whereas Δα is strongly affected by the nature of the substituents and by the molecular geometries. According to Prasadʹs equation, γorient was calculated from Δα and compared with experimental values.