Interaction potential nonempirical

A. Wallqvist and G. Karlstrbm, Chem. Scripta, 29A, 131 (1989). A New Nonempirical Force Field for Computer Simulations. (This NEMO method of this paper should not be confused with the earlier molecular orbital method with the same name see M. D. Newton, F. P. Boer, and W. N. Lipscomb, /. Am. Chem. Soc, 88, 2353 (1966). Molecular Orbitals for Large Molecules.) C. E. Dykstra, Chem. Rev., 93,2339 (1993). Electrostatic Interaction Potentials in Molecular Force Fields. 

It should represent the true potential accurately in the interaction regions for which experimental or nonempirical theoretical data are available. 

The interaction parameters for the water molecules were taken from nonempirical configuration interaction calculations for water dimers (41) that have been shown to give good agreement between experimental radial distribution functions and simulations at low sorbate densities. The potential terms for the water-ferrierite interaction consisted of repulsion, dispersion, and electrostatic terms. The first two of these terms are the components of the 6-12 Lennard-Jones function, and the electrostatic term accounts for long-range contributions and is evaluated by an Ewald summation. The... 

Hobza P, Kabelac M, Sponer J, Mejzlik P, Vondrasek J (1997) Performance of empirical potentials (AMBER, CFF95, CVFF, CHARMM, OPS, POLTEV), semiemprical quantum chemical methods (AMI, MNDO/M, PM3) and ab initio Hartree-Fock method for interaction of DNA bases comparison of nonempirical beyond Hartree-Fock results, J Comp Chem, 18 1136-1150... 

Some references to particularly pertinent molecular-orbital or configuration-interaction calculations of potential curves of diatomic molecules will be mentioned below in this section. These references are not intended to be exhaustive but should serve to indicate some of the calculations which have been carried out and the type of information which is available. (The most comprehensive compilation of nonempirical molecular-orbital calculations is a 1967 survey by Krauss [33], which includes both diatomic and polyatomic molecules.)... 

W. A. Sokalski, A. H. Lowrey, S. Roszak, V. Lewchenko, J. Blaisdell, P. C. Hariharan, and J. J. Kaufman,/. Comput. Chem., 7,693 (1986). Nonempirical Atom-Atom Potentials for Main Components of Intermolecular Interaction Energy. 

Using the nonempirical pseudopotential proposed by Barthelat et al. [22], the two Li+ ions and the Xe atom are treated as a three cores interacting with the alkali valence electron. Based on this approach, the total potential of the Li2" (x2Sg+) system is a sum of three contributions the valence electron-core interaction, corecore interactions, and the three-body interactions. In this context, the total potential is given by ... 

In order to calculate the optimal tunneling distances with the help of Equation (7.3), we must know the parameters b and p. For unbonded C and H atoms, these parameters have been obtained empirically from molecular conformation data as well as from the structure and properties of molecular crystals[447]. However, their values, and in particular the parameter p = 0.22, have been chosen in such a way that they provide the best description for the interaction at distances close to the sum of van der Waals radii. But, as will be clear from subsequent calculations, the proton transfer occurs at considerably smaller interatomic distances which are of the order of the sum of ionic radii. At these distances, all empirical potentials adapted for the purpose of conformational analysis lead to a sharper increase in the energy of repulsion than the potentials obtained from nonempirical calculations and from experimental data on atomic col-lisions[447]. Therefore, it seems more appropriate to carry out the calculations by taking the value of p = 0.35 A, which is characteristic for ionic crystals whose nuclei are much closer to each other[448]. In this case, the parameter b was chosen in such a way that the value of U coincided with the energy of repulsion in molecular crystals for small derivations (0.4 A) from the sum of van der Waals radii. 

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