Molecular quadrupole moments of HCCH, FCCF, and ClCCCl



The molecular quadrupole moments of HCCH, FCCF, and ClCCCl have been studied as a function of basis set at the self-consistent field, density functional theory (B3LYP), and CCSD(T) levels. The CCSD(T) results, in units of eamath image, are 4.856 (HCCH), −0.6389 (FCCF), and 3.7685 (ClCCCl). When corrected for vibration, the HCCH result is reduced to 4.795 and is in excellent agreement with experiment, 4.71 ± 0.14. There are no experimental data for FCCF and ClCCCl. The molecular quadrupole moments are shown to have the form Θ = Θatoms + Θcr, where Θatoms is the sum of the quadrupole moments of the separated atoms and Θcr is the contribution due to charge redistribution upon molecule formation. This model accounts for the magnitude and signs of Θ in this series. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003