Calculation of molecular polarizabilities using a semiclassical Slater-type orbital-point dipole interaction (STOPDI) model

Abstract

The point dipole interaction model for molecular polarizability proposed by Applequist, Carl, and Fung [J. Am. Chem. Soc. 94, 2952 (1972)] is modified by replacing the point dipole interaction tensor with a descaled distributed charge interaction tensor. Our procedure is based on the descaled tensor algorithm proposed by Thole [Chem. Phys. 59, 341 (1981)] and uses a Slater-type orbital (STO) function to represent the charge distribution. The resulting STOPDI formalism calculates mean molecular polarizabilities and the components of the molecular polarizabilities with errors comparable to experimental uncertainty. Furthermore, these procedures require only one optimized parameter per atom, the average atomic polarizability. The formalism is invariant to coordinate transformations and avoids the discontinuities and/or false resonances that are characteristic of previous classical and semiclassical formalisms. The STOPDI algorithm requires less parameterization and computation time than the anisotropic atom point dipole interaction (AAPDI) model of Birge [J. Chem. Phys. 72, 5312 (1980)] and is more reliable for the calculation of polarizability derivatives and Raman cross sections. We demonstrate, however, that none of the above formalisms are reliable for calculating absolute Raman cross sections for normal modes involving significant bond stretching components. This is an inherent limitation of any formalism which does not explicitly account for electron density redistribution accompanying changes in the internuclear distances of covalently bonded atoms.

Normal mode theory of two step relaxation in liquids: Polarizability dynamics in CS2

“…͑10͒, we conclude that the PAPA is over estimating the polarizability derivative by almost a factor of 5. Similar results have been found by other workers other attempting 27,28 to obtain polarizability derivatives from the PAPA. This conclusion is also consistent with the intensity measurements of Cox, Battaglia, and Madden, 29 who found that the ratio, I Ray /I Ram , of the depolarized Rayleigh intensity to the symmetric stretch Raman, was ϳ1000 for the normal liquid.…”

“…Several modifications of the PAPA have been proposed. 27,28,30 After all, the assumption that atoms in molecules are point isotropic polarizabilities interacting via the unmodified dipole tensor is a radical simplification; short range corrections for even unbonded rare gas atoms 31 have been often discussed in the literature. The approach of Applequist and Quicksall 27 is simple and appealing for our purposes.…”

Assessing Polarizability Models for the Simulation of Low-Frequency Raman Spectra of Benzene

“…A number of approaches have been proposed to account for this shortcoming. 32,[34][35][36] Here we follow the approach of Thole, who developed a field tensor in which one of the interacting sites is smeared out in space. 34,35 The Thole interaction tensor damps the interactions at short distances and prevents polarizability singularities in the event that two or more sites make contact during a simulation.…”

Calculation of off‐resonance Raman scattering intensities with parametric models

“…[18] Subsequently, the model was extended by introducing anisotropic atomic polarizabilities, [24] by allowing the charge transfer between the atoms to occur, [25] and by considering interactions between distributed dipoles. [26,27] ADIM was widely used in the computation of polarizabilities, while the application of the model for studying the Raman scattering intensities is more limited. Applequist and Quicksall [28] used ADIM to compute the derivatives of the polarizability tensor of methane and halomethanes in the normal vibrational modes of these molecules.…”