Atomic Mean Dipole Moment Derivatives and GAPT Charges

Abstract

Mean dipole moment derivatives determined from gas-phase infrared fundamental intensity data for 30 molecules are compared with Generalized Atomic Polar Tensor (GAPT) charges calculated from wave functions obtained with 6-31G(d,p) and 6-311++G(3d,3p) basis sets at the Hartree-Fock, B3LYP density functional, and MP2 electron correlation levels. With very few exceptions, the MP2 results are in better agreement with the experimental values than are the B3LYP results calculated with the same basis set, although the differences between these calculated results are often small. The Hartree-Fock results deviate most from the experimental values. For all atoms studied here, C, H, F, Cl, N, O, and S, the MP2/6-311++G(3d,3p) results agree most closely with the experimental values with rms errors of 0.059, 0.013, 0.044, 0.045, 0.030, 0.041, and 0.014e respectively. Although the calculated results for charges between -0.5 and +0.5e seem to deviate randomly from the experimental results, calculated charges ranging from +0.5 to +2.0e tend to be slightly larger than the experimental values. This is a consequence of the fact that the MP2/6-311++G(3d,3p) calculations tend to overestimate infrared intensity sums for molecules with more polar bonds and intensity sums above 500 km mol -1 . The results reported here show that the calculated charge values seem to be converging to the experimental values as the basis set becomes more extensive, 6-31G(d,p) to 6-311++G(3d,3p), and as the electron correlation level becomes more complex, Hartree-Fock to B3LYP density functional to MP2. Experimental mean dipole moment derivative values are shown to be consistent with trends in atomic charge values expected from chemical arguments for the halomethanes, hydrocarbons and Group IV hydrides.

Theoretical study on the structure and formation mechanism of [C6H5Mm]− (MAg, Au; m = 1–3)

“…All energies reported here are corrected with the zero‐point vibrational energy (ZPVE). Since recent reports39, 40 seem to indicate that the charges evaluated using the atomic polar tensors (APT) are more representative of the electron density distributions and are also relatively insensitive to basis set variations, to carry out charge analysis, we have computed the APT charges from the calculated wave functions of the optimized geometries of these complexes.…”

The role of electronic properties to the mutagenic activity of 1,6- and 3,6-dinitrobenzo[a]pyrene isomers

“…As reported in the literature, dipole moment derivatives can be estimated experimentally from infrared intensities and can be accurately determined by means of quantum-mechanical computations [34,35,49]. For the nitro group in positions 1 and 3, B3LYP/6-31G* qNO 2 (APT) value is substantially negative, being calculated to be −0.134 and −0.129 e, respectively.…”

Atomic charge transfer-counter polarization effects determine infrared CH intensities of hydrocarbons: a quantum theory of atoms in molecules model

“…This behavior was also observed in our previous MP2/6-311++G(3d,3p) study for the high intensity bands of a diverse group of thirty molecules. 43 Table 2 contains the root mean square (rms) error values for each molecule and each quantum level and basis set combination.…”