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-change-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 accuracy of our model. It is shown that the EFG tensor components calculated by applying the PCNQM model at the Hartree–Fock and second-order Møller–Plesset level of theory are in excellent agreement with analytically derived expectation values.