Simple point charge model

The EFGs for both 69,7 Ga and 14N have been calculated using the WIEN-97 program, and the results compare more favorably with the experimental results than do those from a simple point charge model including Stemheimer antishielding factors (note that the experimental 14N NQCC value used in the comparison was somewhat larger than the accurate value reported above) [52]. 

O.A. Karim et al., The ice/water interface A molecular dynamics simulation using the simple point charge model. J. Chem. Phys. 92, 4634 1635 (1990)... 

Such an order is difficult to rationalize in terms of electrostatic energies embodied in the simple point-charge model of crystal field theory. For example, the charged O2- anion precedes the dipolar H20 molecule in the spectrochemical series. Note that the spectrochemical series differs from the nephelauxetic series discussed in chapter 11 (eq. 11.6), which is a measure of the degree of covalent bonding. 

Glattli A, Daura X, van Gunsteren WF (2003) A novel approach for designing simple point charge models for liquid water with three interaction sites, J Comput Chem, 24 1087-1096... 

The Effects of Pressure on Structural and Dynamical Properties of Associated Liquids Molecular Dynamics Calculations for the Extended Simple Point Charge Model of Water. 

Procedures for evaluating activation parameters range from simple continuum models to full-blown molecular-level simulations (molecular dynamics, MD, or Monte Carlo, MC) at either a classical or quantal level [15, 21, 33, 36, 47, 49, 52a, 84b, 94, 119]. In such treatments, the DBA system may be represented by a simple point-charge model or one based on a detailed electronic structure calculation, which can, if desired, be self-consistently adjusted to the response of the medium [119]. 

This is obviously not the case if the solvent electronic polarizability is treated explicitly (as discussed earlier) because it will respond differently to the different charge distributions in the two electronic states. If one uses the simple point charge model for the solute and solvent molecules, then the dependence of the... 

K. Bagchi, S. Balasubramanian, and M. L. Klein,/. Chem. Phys., 107, 8561 (1997). The Effects of Pressure on Structural and Dynamical Properties of Associated Liquids Molecular Dynamics Calculations for the Extended Simple Point Charge Model of Water. 

Figure 6. Hypothetical coupling of length scales in the attachment of two hydroxylated oxide nanoparticles in aqueous solution. The crystal cores are represented by continuum finite elements with elastic moduli Xy and dielectric tensor sy. The far-field continuum solvent has viscosity p, dielectric constant s, and exerts random boundary forces Fstoch on the fluid inside the large sphere modeled using particle methods. SPC is a simple point charge model for water.

Hummer G, Grdnbech-Jensen N, Neumann M. Pressure calculation in polar and charged systems using Ewald summation results for the extended simple point charge model of water. J. Chem. Phys. 1998 109 2791. 

The SHAKE tolerance for the bond-stretch constraints is the same in both procedures [(s/ ) = 10 ], and the bond-angle tolerance in the angle-constraint approach is obtained from Eq. [119] [(af) 10 ]. The accuracies of the two approaches are comparable for the adopted values of tolerances. SPC/E designates a modified simple point charge model. 

These difficulties may be alleviated by imposing theoretical constraints. First of all, a theoretical model of the crystal-field interaction can be compared with crystal-field parameters that correspond to the various minima, and the best set selected on the basis of agreement with the model. The simple point charge model extended by means of the three-parameter theory (Leavitt et al., 1975) is a step in this direction. Additional guidance at a more phenomenological level can be provided by the superposition model (Bradbury and Newton, 1967). Theoretical models can also be used to provide a set of starting parameters in the search for the correct minimum. 

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