Electric moments of carbon dichalcogenides

Abstract

The dipole and quadrupole moments and parallel dipole polarizabilities of the carbon dichalcogenides XCY (X, Y = O, S, Se and Te) are evaluated at the level of the CCSD(T) approximation with HyPolX basis sets. The relativistic effects are taken into account by using the scalar version of the two-component Douglas–Kroll method. The reported calculations provide a systematic study of the electron correlation and relativistic effects in the investigated series of carbon dichalcogenides and their results agree well with best-known experimental data. Particular attention has been given to the OCS molecule and the present calculations combined with recent studies by other authors may help to resolve the ambiguities concerning its quadrupole moment. Changes of dipole and quadrupole moments in the studied series of molecules are interpreted in terms of the electronegativities of the chalcogene atoms and their changes due to relativistic effects. The latter have been found to lead to significant changes in the calculated quadrupole moments of the heavy members of the series of molecules. Study of the basis set dependence of the calculated data shows that both the earlier PolX and the recently developed HyPolX basis sets are suitable for calculations of reliable values of the low-multipole moments and dipole polarizabilities of molecules containing heavy elements.