Force electronic effects

The driving forces resulting in these inclusion complexes are attribnted to various factors such as hydrophobic interactions, van der Waals forces, electronic effects, and steric factors. These interactions make them behave like enzymes to yield high specificity and reaction rates, especially in water. 

Induced dipole/mduced dipole attraction (Section 2 17) Force of attraction resulting from a mutual and complemen tary polanzation of one molecule by another Also referred to as London forces or dispersion forces Inductive effect (Section 1 15) An electronic effect transmit ted by successive polanzation of the cr bonds within a mol ecule or an ion... 

Molecular mechanics calculations don t explicitly treat the electrons in a molecular system. Instead, they perform computations based upon the interactions among the nuclei. Electronic effects are implicitly included in force fields through parametrization. 

Following a description of femtosecond lasers, the remainder of this chapter concentrates on the nuclear dynamics of molecules exposed to ultrafast laser radiation rather than electronic effects, in order to try to understand how molecules fragment and collide on a femtosecond time scale. Of special interest in molecular physics are the critical, intermediate stages of the overall time evolution, where the rapidly changing forces within ephemeral molecular configurations govern the flow of energy and matter. 

The effects of benzaldehyde concentrations on turnover frequency are anomalous. Our results indicate that benzaldehyde hydrogenation turnover frequency is independent of benzaldehyde concentration (an apparent zero-order dependence). However, the data in Table 2 indicate otherwise. If the reaction were independent of aldehyde concentration, the rate data should be independent of the type of aldehyde used. This is especially true with p-tolualdehyde and p-anisaldehyde where the structural changes to the aldehyde (addition of p-methyl or p-methoxy) should influence the reactivity of the aldehyde functionality only through electronic effects. Thus, we are forced to conclude that the aldehyde is involved in the rate determining step even though the concentration study does not support its presence. 

To date, the only applications of these methods to the solution/metal interface have been reported by Price and Halley, who presented a simplified treatment of the water/metal interface. Briefly, their model involves the calculation of the metal s valence electrons wave function, assuming that the water molecules electronic density and the metal core electrons are fixed. The calculation is based on a one-electron effective potential, which is determined from the electronic density in the metal and the atomic distribution of the liquid. After solving the Schrddinger equation for the wave function and the electronic density for one configuration of the liquid atoms, the force on each atom is ciculated and the new positions are determined using standard molecular dynamics techniques. For more details about the specific implementation of these general ideas, the reader is referred to the original article. ... 

The effect of the relative electronegativity of a substituent (R) and/or the delocalization of electrons on a chemical property of a substance. Thus, for a molecule R—R, the polar effect refers to all nonsteric influences and modifications of electrostatic forces operating at the reaction center (R ), relative to some standard molecule, Rq—R. Hence, the term is synonymous with the electronic effect. 

Ciraci, S., Baratoff, A., and Batra, I. P. (1990a). Site-dependent electronic effects, forces, and deformations in scanning tunneling microscopy of flat metal surfaces. Phys. Rev. B 42, 7618-7621. 

The dissolution of a solute in a solvent always affects the solvent-solvent interactions in the vicinity of the solnte particles in addition to the solnte-solvent interactions that take place (Marcus, 1998b). This may be viewed in several stages. First, a cavity in the solvent is formed, to accommodate the solute, which breaks down the cohesive forces of the solvent. Next dispersion forces take effect. They apply to nonpolar and hardly polarizable solutes and solvents, as well as to polar and polarizable ones. Other forces that become active provide contributions from interactions of polar molecnles with polar or polarizable ones and from donor acceptor interactions, such as electron-pair or hydrogen-bond donation and acceptance, whether from or to the solute, the solvent, or both. 

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