Exchange potential dipole moments

The parametrization procedure that we have opted for in the most recent works is as follows (1) Compute the intermolecular dynamic correlation energy for the ground state with a second-order Mpller-Plesset (MP2) expression that only contains the intermolecular part and which uses monomer orbitals. Fit the dispersion parameters to this potential. To aid in the distribution of the parameters, a version of the exchange-hole method by Becke and Johnson is sometimes used [154,155], Becke and Johnson show that the molecular dispersion coefficient can be obtained fairly well by a relation that involves the static polarizability and the exchange-hole dipole moment ... 

It is clear that intermolecular force and induced dipole function arise from the same physical mechanisms, electron exchange and dispersion. Since at the time neither intermolecular potentials nor the overlap-induced dipole moments were known very dependably, direct tests of the assumptions of a proportionality of force and dipole moment were not possible. However, since the assumption was both plausible and successful, it was widely accepted, even after it was made clear that for an explanation of... 

Figure 8.9 DPV of phenylethanethiolate protected Au MPCs (black), and mixed protected Au MPCs with phenylethanethiolate and Aib peptides modified by ligand exchange (gray) showing significant shift in redox potentials due to Aib peptide induced shift in particle dipole moment.42 (Reprinted with permission from A. H. Holm et al., Langmuir 2006, 22, 10584-10589. Copyright 2006 American Chemical Society.)...

Electrochemistry shares many concepts with surface science, and for the last two decades there has been an exchange of methods and ideas between these two neighboring disciplines. However, the electrosorption valency has no equivalent in surface science, since experiments at the solid/gas or solid/vacuum interface cannot be performed at constant potential. However, for low coverages, and near the potential of zero charge, the electrosorption valency can be related to the dipole moment of the adsorbate, which can be measured both in surface science and, though with greater difficulty, also in electrochemistry. In the following, we point out the relation between these two quantities. 

An alternative way of calculating the static polarizability is to evaluate the induced electric dipole moment by applying an external electric field in the SCF calculations, as described in section III. Variation of the induced dipole moment as a function of the applied electric field in the SCF calculations for Ceo is shown in Fig. 21 for the Hedin-Lundquvist exchange-correlation potential and an extended basis set. The calculations were performed using an electric field of strength up to 0.032 a.u. corresponding to 0.16-10 Vm . ... 

Most of the potential energy surfaces reviewed so far have been based on effective pair potentials. It is assumed that the parameterization is such as to account for nonadditive interactions, but in a nonexplicit way. A simple example is the use of a charge distribution with a dipole moment of 2.ID in the ST2 model. However, it is well known that there are significant non-pairwise additive interactions in liquid water and several attempts have been made to include them explicitly in simulations. Nonadditivity can arise in several ways. We have already discussed induced dipole interactions, which are a consequence of the permanent diple moment and polarizability of the molecules. A second type of nonadditive interaction arises from the deformation of the molecules in a condensed phase. Some contributions from such terms are implicitly included in calculations based on flexible molecule potentials. Other contributions arises from electron correlation, exchange, and similar effects. A good example is the Axilrod-Teller three-body dispersion interaction ... 

Dalton s atomic theory, overview, 1 De Broglie equation, 23 Delocalization energy, definition, 174 Density functional theory chemical potential, 192 computational chemistry, 189-192 density function determination, 189 exchange-correlation potential and energy relationship, 191-192 Hohenberg-Kohn theorem, 189-190 Kohn-Sham equations, 191 Weizsacker correction, 191 Determinism, concept, 4 DFT, see Density functional theory Dipole moment, molecular symmetry, 212-213... 

Calculated DFT properties listed in Table 1 were obtained from the fit of the ground-state potential energy curves to 12 points calculated around the energy minimum [32]. Dissociation energy has been corrected for basis set superposition error by a standard counterpoise technique. The local approximation to the exchange and correlation gives the best fit to bond distances, theoretical values differ by no more than 0.03 A (4%) from the experimental ones (see Table 1). Vibrational frequencies are also predicted to lie within 1 % off the experiment. One should remember, however, that other advanced quantum chemical methods give equally satisfactory results for these, basicaly one-electron quantities and that inclusion of nonlocal effects does not improve the DFT predictions. The dipole moment, fi, is much more sensitive... 

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