Adiabatic pair potentials

Sogami, I. S.,T. Shinohara, andM. V. Smalley. 1992. Adiabatic pair potential of highly charged plates in an electrolyte. Molecular Physics An International Journal at the Interface between Chemistry and Physics 76, no. 1 1. doi 10.1080/00268979200101121. 

The comparison with adiabatic ionization potentials [147] indicates that the latter decrease as electronic charge builds up on nitrogen, as one would normally expect, thus suggesting that the charges calculated here are in the right order. (These ionization potentials correspond to the suppression of an electron of the lone pair on... 

Comparison of adiabatic ionization potentials (IP) of normal and branched alkanes with carbon net charges, which indicates a lowering of the IPs with increasing electron population of the electron-richest bonded pair of carbon atoms in the molecule [170]. A monotonic correlation (which turns out to be linear and remarkably accurate) is possible only with atomic charges adjusted for n = 4.4083 and the corresponding p given by Eq. (5.14). 

The screening term describes the screening of Coulomb potential due to the overlap of electronic densities of ions. Parameters of the pair potential model are listed in Table 1. The many-particle JT contribution to the crystal energy is approximated by the sum of expressions for the lower brunches of adiabatic potentials of the Mn06 clusters... 

The development of electronic geometric phase factors is governed by an adiabatic vector potential induced in the nuclear kinetic energy when we extend the Born-Oppenheimer separation to the degenerate pair of states [1, 23-25]. To see how the induced vector potential appears, we consider the family of transformations which diagonalize the excited state electronic coupling in the form... 

Methods for obtaining values of aX for gas-phase neutrals and cations have been described in the literature (7). Estimates of adiabatic electron affinities (M ") and adiabatic ionization potentials (alP, ) of neutral molecules have been obtained in many cases through investigations of charge-transfer equilibria between pairs of neutral molecules and their parent ions. EA values for over two hundred compounds have been determined that span a range of -0.8 to 3 eV (76), and a large number of alP values have also been reported (77). Charge-transfer equilibria (Equation 10) for cations or... 

On the addition of fours waters the adiabatic ionization potentials of the purines in base pairs slightly increase (ca. 0.3eV), but to a lesser extent than the increase for the Koopmans ionization potentials after water addition. This is expected as relaxation of the nuclear framework in the adiabatic calculation allows the hydration shell to adjust to the formation of the cation radical. To investigate the effects of additional solvation layers on the adiabatic ionization... 

Figure 3 Base pairing, primary hydration, stacking and full solvation effects on the adiabatic ionization potentials of the DNA bases calculated at 6-31+G(d)//3-21G and corrected by 0.82eV [52], A dielectric constant of 2 simulates base pair stacking a dielectric constant of 78 simulates full solvation in the Born-Onsager model. n=3 in GC n=4 in AT. Reproduced with permission from ref. [52].

Vo + V2 and = Vo — 2 (actually, effective operators acting onto functions of p and < )), conesponding to the zeroth-order vibronic functions of the form cos(0 —4>) and sin(0 —(()), respectively. PL-H computed the vibronic spectrum of NH2 by carrying out some additional transformations (they found it to be convenient to take the unperturbed situation to be one in which the bending potential coincided with that of the upper electi onic state, which was supposed to be linear) and simplifications (the potential curve for the lower adiabatic electi onic state was assumed to be of quartic order in p, the vibronic wave functions for the upper electronic state were assumed to be represented by sums and differences of pairs of the basis functions with the same quantum number u and / = A) to keep the problem tiactable by means of simple perturbation... 

For a given molecule and a given intemuclear separation a would have a definite value, such as to make the energy level for P+ lie as low as possible. If a happens to be nearly 1 for the equilibrium state of the molecule, it would be convenient to say that the bond is an electron-pair bond if a is nearly zero, it could be called an ionic bond. This definition is somewhat unsatisfactory in that it does not depend on easily observable quantities. For example, a compound which is ionic by the above definition might dissociate adiabatically into neutral atoms, the value of a changing from nearly zero to unity as the nuclei separate, and it would do this in case the electron affinity of X were less than the ionization potential of M. HF is an example of such a compound. There is evidence, given bdow, that the normal molecule approximates an ionic compound yet it would dissociate adiabatically into neutral F and H.13... 

Fig. 5. Contour plot of the adiabatic potential-energy surface of an H atom in the (110) plane for the neutral H—B pair from a local-density pseudopotential calculation. The boron atom is at the center. For every hydrogen position, the B and Si atoms are allowed to relax, but only unrelaxed positions are indicated in the figure (Reprinted with permission from the American Physical Society, Denteneer, P.J.H., Van de Walle, C.G., and Pantelides, S.T. (1989). Phys. Rev. B 39, 10809.)...

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