An electron momentum spectroscopy study of the outer valence orbitals of chlorodifluoromethane

Electron momentum spectroscopy (EMS) has been used to measure the momentum profiles of outer valence orbitals of chlorodifluoromethane (CHF2Cl), which are compared with Hartree-Fock (HF) and density functional theory (DFT) calculations using different-sized basis sets. Overall, DFT calculation employing B3LYP hybrid functional and the largest basis set that we used provides the best agreement with experiment. But the minimum improvement gained by replacing the 6-311++G** basis set with AUG-cc-pVQZ suggests that basis set saturation has been approached, at least for some orbitals of CHF2Cl, and a computationally affordable method which addresses effects that current theoretical treatment neglects, such as distorted wave and electron relaxation, is sorely needed. (C) 2003 Elsevier B.V. All rights reserved.