The atom dipole interaction model of Raman optical activity: Reformulation and comparison to the general two-group model

Abstract

A variational method in twogroup transport theory An atom-dipole interaction theory of the hyperpolarizability contribution to the optical activity of moleculesThe atom dipole interaction (ADI) model of Raman optical activity (ROA) is reformulated and the ADI expressions for the induced polarizabilities are presented in Cartesian tensor notation. These revised expressions are compared with those of the general two-group (GTG) model. It is shown that the ADI model incorporates antisymmetric tensor contributions to the polarizability which is an important source of optical activity not included in the GTG model. The ROA intensity parameters for the HCBrClF and DCBrClF are presented and the importance of the antisymmetric tensor contributions in this molecule is demonstrated.5582

Vibrational optical activity

“…Calculations of the ROA observables, which are usually based on the Placzek approximation, can proceed in several ways. Models of ROA exist such as the atom dipole interaction model [67] and the bond-polarizability model [2,68]. In the bond-polarizability model the molecule is decomposed into bonds or groups supporting local internal vibrational coordinates.…”

Raman Optical Activity of Biological Samples

“…this multiplicity is a result of the existence of a variety of theoretical models of RoA [44][45][46]. Calculation by using such RoA models as the atom-dipole interaction [47] and the bond-polarizability [13,48] didn't result in broad satisfactory results. however, they can still provide valuable physical insight into the generation of RoA [13,45].…”

The bond polarizability theory of Raman optical activity calculations on (R) - (+) bromochlorofluoromethane

“…Calculated polarized (Ax) and depolarized (Az) Raman circular intensity differences for (R)-(+) bromochlorofluoromethane. (a) Bond polarizability (this work), (b) atom dipole interaction (from [4] Theory of Raman optical activity 849 could find no published value for the derived anisotropy of the C-F bond and so guessed a value of 2.2252 x 10 -3o Fm (2.0 x 10 -~e cm z in mixed gaussian units [37]) ; adjusting this by + 1.1126 x 10 -s° Fm( + 1.0 x 10 -~6 cm 2) did not alter any of the Raman optical activity signs predicted by the calculation. This scavenging for the bond polarizability parameters is most unsatisfactory since very different values are often quoted in different studies and the choice is rather arbitrary, leading to some inconsistencies.…”

“…Furthermore, a reliable force field has been published [30], work has been done on the bond polarizability derivatives of various halogenated alkanes [11,31,32] and the molecule has already been the subject of several detailed theoretical studies of both the infrared [33] and Raman [3,4] vibrational optical activity. Unfortunately the molecule is difficult to resolve and no reliable vibrational optical activity spectra have been published.…”

“…Consequently, much effort has been directed to the development of general theories, based on a full normal coordinate analysis, which can compute the sign and magnitude of the vibrational optical activity in every normal mode. In the Raman case several such calculations, based on an atom dipole interaction theory have been published [3][4][5][6][7], and a localized molecular orbital theory has been mooted [8]. Here we present an alternative calculational method based on the bond polarizability theory of Raman intensities.…”