Extension of the PCNQM model for the calculation of electric field gradient tensors in asymmetric molecules. The carbon electric field gradient in CH3CHFCl

The point charge nuclear quadruple moment (PCNQM) model for the picture-cha nge-error free determination of electric field gradients (EFG) is extended to systems with low symmetry in order to determine the full EFG tensor. The carbon EFG tensor in 1-fluoro-1-chloroethane was chosen to test the accura cy of our model. It is shown that the EFG tensor components calculated by a pplying the PCNQM model at the Hartree-Fock and second-order Moller-Plesset level of theory are in excellent agreement with analytically derived expec tation values. (C) 2000 Elsevier Science B.V. All nights reserved.