Electrostatic dipole

In connection with electronic strucmre metlrods (i.e. a quantal description of M), the term SCRF is quite generic, and it does not by itself indicate a specific model. Typically, however, the term is used for models where the cavity is either spherical or ellipsoidal, the charge distribution is represented as a multipole expansion, often terminated at quite low orders (for example only including the charge and dipole terms), and the cavity/ dispersion contributions are neglected. Such a treatment can only be used for a qualitative estimate of the solvent effect, although relative values may be reasonably accurate if the molecules are fairly polar (dominance of the dipole electrostatic term) and sufficiently similar in size and shape (cancellation of the cavity/dispersion terms). 

Kaminski GA, Friesner RA, Zhou RH (2003) A computationally inexpensive modification of the point dipole electrostatic polarization model for molecular simulations. J Comput Chem 24(3) 267-276... 

The dipole-dipole electrostatic interaction and a repulsiveterm that avoids collapsing of dipoles was expressed as ... 

While the structure of clusters responds to directionally specific electrostatic interactions, their stabilization energy reflects also the intervention of less specific dispersion interactions. This is, e.g., the case for stacked DNA base pairs. Stability of these pairs stems from dispersion energy while their structure is determined by dipole-dipole electrostatic interactions. Dispersion energy plays an important role in stabilizing clusters of biomacromolecules, where it may be the dominant attractive term. 

Figure 4.3 Schematic showing dipole-dipole electrostatic interactions between the negatively and positively charged ends of different water molecules which form the basis of hydrogen bonding. (From Henshaw et al., 2000, with permission.)...

Hydrogen bonding dipole-dipole electrostatic interactions between the negatively and positively charged ends of different water molecules. 

Dipole-dipole electrostatic interaction perturbs the randomness of orientation. If the dipole on the left is pointing "up," then there is a slightly greater chance that the dipole on the right will point "down" (or vice versa both particles are equivalent in mutual perturbation). By increasing the chances of an attractive mutual orientation, the perturbation creates a net-attractive interaction energy. 

Kaminski, G. A., Friesner R. A. and Zhou R., A Computationally Inexpensive Modification of the Point Dipole Electrostatic Polarization Model for Molecular Simulations. J.Comput.Chem. (2003) 24 267-276. 

Regardless of the kinetic regioselectivity, Fraser, Houk and coworkers have demonstrated that the nitrogen substituents of most metallated (litiiio) aldehyde- and ketone-derived azomethines prefer the (Z)-orientation (Scheme 2). This thermodynamic preference is postulated to result hrom a minimization of dipole-dipole (electrostatic) interaction between nitrogen lone pair electrons and the carbanion. 

Relationships analogous to those of Eqs. (37) have been used previously (72, 13) for the comparison of the angular-overlap model and the point-charge or point-dipole electrostatic model. 

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