Theory rotational strength

The quantity that connects theory with experiment in CD spectroscopy is the rotational strength R. On an experimental level, R is determined by the area under a resolved CD transition (Figure 1.6b), while from theory the rotational strength is proportional to the projection of the electric dipole moment of a T g —> vPe transition... 

Cheeseman JR, Frisch MJ, Devlin FJ etal (1996) Ab initio calculation of atomic axial tensors and vibrational rotational strengths using density functional theory. Chem Phys Lett 252 211-220... 

Maradudin AA, Montroll EW, Weiss GH, Ipatava P (1971) Theory of lattice dynamics in the harmonic approximation. Academic Press, New York March N (1992) Electro Density Theory of atoms and molecules. Academic Press Marcott C, Havel HA, Hedlund B, Overend J, Moscowitz A (1979) A vibrational rotational strength of extraordinary intensity. Azidomethemoglobin A. In Mason SF (cd) Optical activity and chiral discrimination, Reidel, Dordrecht, p 289... 

The rotational strength is theoretically expressed by Equation (10), which was derived by Rosenfeld in the early days of the development of quantum mechanical theory. 

Finally, on carrying the treatment of the concunent T2 and T2g crystal field potentials to all orders of perturbation theory, it has been established ), for a wide range of parameter sets, that the computed rotational strengths are at variance quantitatively and in qualitative form with the conesponding experimental values, measured from the CD band areas. In particular, the rotational strengths of the d—d transitions to the D3 cobalt(IIl) states, A2 and E with a common octahedral parent-... 

R. A. Harris, Oscillator strengths and rotational strengths in Hartree-Fock theory, J. Chem. Phys. 50 (1969) 3947. 

Figure 5 shows schematically the distributions of rotational strengths predicted by Equation 2 for adenylate oligomers as single-chain helices with eight residues per turn (a = 45°). To estimate the band splittings, we have used the fact that the nearest-neighbor theory predicts that the absorption band of the infinite, stacked-base helix will be shifted from the monomer band by an amount (2 V cos a)/h. Since this shift is experimentally known, V can be eliminated from Equation 1. 

The theoretical basis of CD is discussed in several reviews.A quantity called the rotational strength, which is a property of a given electronic or vibrational transition, generally provides the connection between theory and experiment in CD. The theoretical definition of the rotational strength is... 

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