Born model

The Born model is based on electrostatic interactions, dielectric permitivity, and orbital overlaps. It has the advantage of being fairly straightforward and adaptable to computational methods. The free energy for the polarization of the solute is expressed as... 

One very popular technique is an adaptation of the Born model for orbital-based calculations by Cramer and Truhlar, et. al. Their solvation methods (denoted SMI, SM2, and so on) are designed for use with the semiempirical and ah initio methods. Some of the most recent of these methods have a few parameters that can be adjusted by the user in order to customize the method for a specific solvent. Such methods are designed to predict ACsoiv and the geometry in solution. They have been included in a number of popular software packages including the AMSOL program, which is a derivative of AMPAC created by Cramer and Truhlar. 

Using a set of (partial) atomic charges is often called the generalized Born model. It can be noted that the Born model predicts equal solvation for positive and negative ions of the same size, which is not the observed behaviour in solvents like H2O. 

Considering the success of fragment methods, which apply additive models for log P predichon, one can assume that addihve approaches may also sahsfactory work for MLP. Indeed, similar to the Generalized Born model, one can consider fragments of molecules as centers of some potenhal functions and use an empirically defined distance function ) to calculate the MLP value by ... 

The Born equation thus derived is based on very simple assumptions that the ion is a sphere and that the solvents are homogeneous dielectrics. In practice, however, ions have certain chemical characters, and solvents consist of molecules of given sizes, which show various chemical properties. In the simple Born model, such chemical properties of ions as well as solvents are not taken into account. Such defects of the simple Born model have been well known for at least 60 years and some attempts have been made to modify this model. On the other hand, there has been another approach that focuses on short-range interactions of an ion with solvent molecules. 

FIG. 2 (a) The Born model [1], (b) The one-layer model proposed by Abraham and Liszi [15]. (From Ref. 10. Copyright the Japan Society for Analytical Chemistry.)... 

Srinivasan J, Trevathan MW, Beroza P, Case DA (1999) Application of a pairwise generalized Born model to proteins and nucleic acids Inclusion of salt effects. Theor ChemAcc 101 426-434. 

We can exploit the new results for packing contributions to reconsider the outer shell contribution in Eq. (33). For ionic solutes, the outer shell term would represent the Born contribution because it describes a hard ion stripped of any inner shell ligands. A Born model based on a picture of a dielectric continuum solvent is reasonable (see Section III,B, and Fig. 9, color insert). With that motivation, we first separate the outer shell term into an initial packing contribution and an approximate electrostatic contribution as... 

Ghosh, A. Rapp, C.S. Friesner, R.A., Generalized Born model based on a surface area formulation, J. Phys. Chem. B 1998,102, 10983-10990... 

To obtain an estimate for the energy of reorganization of the outer sphere, we start from the Born model, in which the solvation of an ion is viewed as resulting from the Coulomb interaction of the ionic charge with the polarization of the solvent. This polarization contains two contributions one is from the electronic polarizability of the solvent molecules the other is caused by the orientation and distortion of the... 

This is true for a class of models such as the Born model, in which the interaction energy in the Hamiltonian is proportional to the charge see Problem 1. 

The Born model of solvation overestimates solvation free energies but indicates the general trends correctly. Potential inversion, as observed in many other systems containing two identical oxidizable or reducible groups separated by an unsaturated bridge (Scheme 1.4), can be rationalized in the same manner. 

Tosi M. P (1964). Cohesion of ionic solids in the Born model. Solid State Phys., 16 1-120. 

Michel, J., Taylor, R.D., Essex, J.W. Efficient generalized born models for Monte Carlo simulations. J. Chem. Theory Comput. 2006, 2, 732-9. 

Structure at high temperatures. A distorted perovskite would be expected to transform to the cubic structure at high temperatures. The Born model of ionic solids with the appropriate repulsive and van der Waals parameters can explain the relative stabilities of crystal structures in partly covalent solids, an ionicity parameter would have to be used to predict the preferred crystal structure (see Chapter 1, Section 1.3). 

Bashford, D. and Case, D. A. 2000. Generalized Born Models of Macromolecular Solvation Effects Annu. Rev. Phys. Chem., 51, 129. 

Kumar, M., Srivastava, R. and Tripathi, A.N. (1985). Systematic approach for discrete excitation of helium in the Coulomb-Born model. Phys. Rev. A 31 652-658. 

Solvent effects for ions can be described by a similar continuum solvent model the so-called Born model. This model predicts a stabilization proportional to the square of the charge, and inversely proportional to the size (radius) of the ion that is, small and highly charged ions are strongly stabilized in solution. 

In the Generalized Born model [2-5], the solvent is described in a extremely simplified way and there is no mutual polarization between solute and solvent. The Onsager model [6] allows for solute-solvent polarization, but the description of the cavity and of the solvent is still very crude. 

Onufriev A, Bashford D, Case DA (2004) Exploring protein native states and large-scale conformational changes with a modified generalized born model. Proteins 55(2) 383-394... 

Solvation in Ligand Binding Free Energy Calculations Using the Generalized-Born Model. 

It would appear that the radii for alkali and halide ions based on experimental electron distribution results for NaCl provide the most realistic set currently available. The values agree well with crystal radii of the ions determined by Fumi and Tosi (77, 26) using the Born model of ionic solids in conjunction with solid-state data for the NaCl-type alkali halides — Table 2. It would be of considerable value if experimental electron distribution data in additional alkali halides were available to confirm the figures, but it appears that there can be important difficulties involved in their measurement (79)3. 

Table 2. Average crystal radii of the alkali and halide ions in the NaCl-type alkali halides obtained using the Born model (Born-Mayer form) (26)...

The information discussed above can, however, yield only the overall trend in transfer quantities, and it would be unrealistic to expect, for example, that in aqueous mixtures, 6m (ion) is a linear function of mole fraction. Nevertheless it is noteworthy that the transfer quantities between pure solvents are not in agreement with trends expected from a simple Born model for ionic solvation. 

Onufriew A, Bashford D, Case DA (2000) Modification of Generalized Born Model Suitable for Macromolecules J. Phys. Chem. B 104 3712... 

Roux B, Hsiang-Ai Yu, Karplus M (1990) Molecular Basis for the Born Model of Ion Solvation. J. Phys. Chem. 94 4683 1688... 

Im WP, MS Lee, CL Brooks III (2003) Generalized born model with a simple smoothing function. J. Comput. Chem. 24 (14) 1691-1702... 

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