Intermolecular electrostatic energy

Cisneros GA, Piquemal J-P, Darden TA (2005) Intermolecular electrostatic energies using density fitting. J ChemPhys 123 044109... 

When the intermolecular electrostatic energy cannot be neglected, we can use the methodology of London [30, 32] to obtain an expression accounting for the effective field" the chromophores experience... 

F. Y. Hansen, G. P. Alldredge, L, W. Bruch, and H. Ttub, . Chem. Phys., 83, 348 (1985). On the Representation of the Electric Charge Distribution in Ethane for Calculations of the Molecular Quadrupole Moment and Intermolecular Electrostatic Energy. 

The relative magnitudes of the thermal energy (kT), electric field poling energy (pF), and the intermolecular electrostatic energy (W) will define the ratio If thermal energy dominates the... 

Spackman, M. A. The use of the promolecular charge density to approximate the penetration contribution to intermolecular electrostatic energies, Chem. Phys. Letters 2005, 418, 154-158 Volkov, A. Coppens, P. J. Comp. Chem. 2004,25, 921-934. 

M. A. Spackman, Chem. Phys. Lett., 418(1-3), 158-162 (2006). The Use of the Promolecu-lar Charge Density to Approximate the Penetration Contribution to Intermolecular Electrostatic Energies. 

The link between UpophiUcity and point charges is given by intermolecular electrostatic interactions (Sections 12.1.1.2, 12.1.3 and 12.1.4 address this topic) and ionization constants. The mathematical relationships between Upophilicity descriptors and pKjS are discussed in detail in Chapter 3 by Alex Avdeef. Here, we recall how pKj values are related to the molecular electron flow by taking the difference between the pfCj of aromatic and aUphatic amines as an example. The pfCa of a basic compound depends on the equilibrium shown in Fig. 12.2(A). A chemical effect produces the stabilization or destabiUzation of one of the two forms, the free energy difference (AG) decreases or increases and, consequently. 

Piquemal J-P, Gresh N, Giessner-Prettre C (2003) Improved formulas for the calculation of the electrostatic contribution to intermolecular interaction energy from multipolar expansion of the electronic distribution. J Phys Chem A 107 10353... 

Gresh N, Piquemal J-P, Krauss M (2005) Representation of Zn(II) complexes in polarizable molecular mechanics. Further refinements of the electrostatic and short-range contribution of the intermolecular interaction energy. Comparisons with parallel ab initio computations. J Comput Chem 26 1113... 

Furthermore, in this scheme of partitioning the formula for AEqov becomes identical with the semiclassical electrostatic energy of interaction (4). As we shall see later a closely related quantity can be defined in the framework of intermolecular MO theory and thereby comparison of different approaches is largely facilitated. 

The intermolecular distance was calculated here relative to the center of mass (C. M.) of the water molecule. For this particular choice of the origin the quadruple term is rather small and the total electrostatic energy of interaction is reproduced fairly well by the first term of the expansion, the ion-dipole term alone. The difference between zIEcou and zIEcou of course is not exclusively... 

FIGURE 1.23 Distributions of (a) electrostatic energies, (b) Van der Waals energies, and (c) total intermolecular energies for 5- and /J-complexes of 0-9-(rcrr-butylcarbamoyl)-6 -neopentoxy-cinchonidine and DNB-Leu sampled during the simulation period of 1 ns in water (top) and chloroform (bottom). (Reprinted from N.M. Maier et al., J. Am. Chem. Soc., 124 8611 (2002). With permission.)... 

In this expression, the dipole dipole interactions are included in the electrostatic term rather than in the van der Waals interactions as in Eq. (9.43). Of the four contributions, the electrostatic energy can be derived directly from the charge distribution. As discussed in section 9.2, information on the nonelectrostatic terms can be deduced indirectly from the charge density. The polarizability a, which occurs in the expressions for the Debye and dispersion terms of Eqs. (9.41) and (9.42), can be expressed as a functional of the density (Matsuzawa and Dixon 1994), and also obtained from the quadrupole moments of the experimental charge density distribution (see section 12.3.2). However, most frequently, empirical atom-atom pair potential functions like Eqs. (9.45) and (9.46) are used in the calculation of the nonelectrostatic contributions to the intermolecular interactions. 

Fig. 20.3 The total intermolecular interaction energy and the first-order electrostatic interaction for 54 structures of guanine-adenine complex...

The results of Table XIX indicate that, in fact, the intermolecular interaction energies are significantly greater in the dimer 86 than in the dimer 87. It may certainly be extrapolated that the same situation would prevail in higher polymers of the two types. It is also interesting to underline that the major part of the bonding energy comes from the electrostatic component. 

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