Triple-dipole energy

Margoliash DJ, Proctor TR, Zeiss GD, Meath WJ (1978) Triple-dipole energies for H, He, Li, N, O, H2, N2, 02, NO, N20, H20, NH3 and CH4 evaluated using pseudo-spectral dipole oscillator strength distributions. Mol Phys 35 747-757... 

Hence, the same teclmiques used to calculate are also used for Cg. Note that equation (A1.5.28) has a geometrical factor whose sign depends upon the geometry, and that, unlike tlie case of the two-body dispersion interaction, the triple-dipole dispersion energy has no minus sign in front of the positive coefficient Cg. For example, for an equilateral triangle configuration the triple-dipole dispersion is repulsive and varies... 

The effect of the Axilrod-Teller term (also known as the triple-dipole correction) is to make the interaction energy more negative when three molecules are linear but to weaken it when the molecules form an equilateral triangle. This is because the linear arrangement enhances the correlations of the motions of the electrons, whereas the equilateral arrangement reduces it. 

In 1980s, it was concluded from neutron diffraction data on krypton that the structure of this sytem could not be described adequately with a single two-boby potential. A supplementary contribution to the energy had to be taken into account, which is the triple-dipole three-body correction [104],... 

Kumar A, Meath WJ (1985) Pseudo-spectral dipole oscillator strengths and dipole-dipole and triple-dipole dispersion energy coefficients for HF, HC1, HBr, He, Ne, Ar, Kr and Xe. Mol Phys 54 823-833... 

The simplest model for the three-body dispersion energy is provided by the well-known triple-dipole expression... 

The MERP in Cj symmetry has the hydroxide ion coplanar with formaldehyde and on the dipole axis at large separations. A shallow minimum was found at a C-0 separation of 2.75 A (4). This ion-molecule complex is separated from 3 by only a 1.1-kcal/mol barrier, as shown by the solid curve in the bottom half of Fig. 3. Thus the existence of the minimum is uncertain at higher levels of theory. Earlier ab initio studies for addition reactions including hydride ion and OH with formaldehyde and OH with formamide have found the tetrahedral intermediate as the only minimum. However, comparatively small basis sets were used, which exaggerates the overall exothermicity. The viability of the ion-molecule intermediates is anticipated to be enhanced by an increased dipole moment, as we found recently for halide ions with acyl halides. The results are consistent with the ideas of Asubiojo and Brauman, though we find both double-well and triple-well energy profiles in the gas phase. 

McDowell SAC, Kumar A, Meath W1 (1996) Anisotropic and isotropic triple-dipole dispersion energy coefficients for all three-body interactions involving He, Ne, Ar, Kr, Xe, H2, N2, and CO. Canad J Chem 74 1180-1186... 

The other non-additive effect which has attracted most attention is the Axilrod-Teller triple-dipole dispersion energy, which for three atoms or rotationally-averaged molecules A, B and C is[30]... 

From a detailed examination of the three-body SAPT energies for the argon liquid, Bukowski et al. (Bukowski and Szalewicz 2001) have concluded that the bulk of the three-body dispersion energy can be estimated using the AxUrod-Teller-Muto triple dipole term. For isotropic local distributed polarizabihties this takes the form (Stone 1996)... 

Figure 4.2. Rotational-energy barriers as a function of substitution. Tbe small barrier ( 2kcal) in ethane (a) is lowered even further ( O.Skcal) if three bonds are tied back by replacing three hydrogen atoms of a methyl group by a triple-bonded carbon, as in methylacetylene (b). The barrier is raised 4.2 kcal) when methyl groups replace the smaller hydrogen atoms, as in neopentane (c). Dipole forces raise the barrier further ( 15 kcal) in methylsuccinic acid (d) (cf. Figure 4.3). Steric hindrance is responsible for the high barrier (> 15 kcal) in the diphenyl derivative (e). (After...

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