Molecular quantum potential

Well-defined products from the chaotic turmoil, which is a chemical reaction, result from a balance between external thermodynamic factors and the internal molecular parameters of chemical potential, electron density and angular momentum. Each of the molecular products, finally separated from the reaction mixture, is a new equilibrium system that balances these internal factors. The composition depends on the chemical potential, the connectivity is determined by electron-density distribution and the shape depends on the alignment of vectors that quenches the orbital angular momentum. The chemical, or quantum, potential at an equilibrium level over the entire molecule, is a measure of the electronegativity of the molecule. This is the parameter that contributes to the activation barrier, should this molecule engage in further chemical activity. Molecular cohesion is a holistic function of the molecular quantum potential that involves all sub-molecular constituents on an equal basis. The practically useful concept of a chemical bond is undefined in such a holistic molecule. 

Finally the most sensitive scheme to differentiate between the shapes of closely related conformers is by comparison of the total overlap energy [148]. It extends the calculation of electrostatic overlap energy (5.8.1) over all pairs of atoms in the molecule. This procedure mimics the calculation of molecular quantum potential even more closely than MM and eliminates the scaling of different types of steric energy. 

Molecular quantum potential and non-local interaction depend on molecular size and the nature of intramolecular cohesion. Macromolecular assemblies such as polymers, biopolymers, liquids, glasses, crystals and quasicrystals are different forms of condensed matter with characteristic quanmm potentials. The one property they have in common is non-local long-range interaction, albeit of different intensity. Without enquiring into the mechanism of their formation, various forms of condensed matter are considered to have well-defined electronic potential energies that depend on the nuclear framework. A regular array of nuclei in a structure such as diamond maximizes cohesive interaction between nuclei and electrons, precisely balanced by the quantum potential, almost as in an atom. 

Bash, P.A., Field, M.J.,Karplus, M. Free energy perturbation method for chemical reactions in the condensed phase A dynamical approach baaed on a combined quantum and molecular dynamics potential. J. Am. Chem. Soc. 109 (1987) 8092-8094. 

Field, M.J., Bash, P.A., Karplus, M. A combined quantum mechanical and molecular mechanical potential for molecular dynamics simulations. J. Comput. Chem. 11 (1990) 700-733. 

Amara P and M J Field 1998. Combined Quantum Mechanical and Molecular Mechanical Potentials. In Schleyer, P v R, N L Allinger, T Clark, J Gasteiger, P A Kolhnan H F Schaefer HI and P R Schreiner (Editors). The Encyclopedia of Computational Chemistry. Chichester, John Wiley Sons. 

Gao J 1995. Methods and Applications of Combined Quantum Mechanical and Molecular Mechanical Potentials. In Lipkowitz K B and D B Boyd (Editors) Reviews in Computational Chemistry Volume 7. New York, VCH Publishers, pp. 119-185. 

Field M J, P A Bash and M Karplus 1990. A Combined Quantum Mechanical and Molecular Mechanical Potential for Molecular Dynamics Simulations. Journal of Computational Chemistry 11 700-733. 

Molecular quantum mechanics finds the solution to a Schrodinger equation for an electronic Hamiltonian, Hgjg., that gives a total energy, Egjg(-(R) + V (R,R). Repeated solutions at different nuclear configurations, R, lead to some approximate potential energy sur-... 

It is worth to remark that the opposite also happens. There is an evolution in the experimental teehniques too, and in some eases this progress makes possible ( or competitive) the measurement of a quantity formerly available via computations only. One example is the detailed measurement of the electronic density of a molecule, and of the related molecular electrostatic potential. The determination of these two observables has been for many years a task feasible only by quantum-mechanical methods, now the progresses in the elaboration of diffraction technique measurements makes possible a direct determination. 

Krauss, M. and Stevens, W.J. (1984) Effective potentials in molecular quantum chemistry. Annual Review of Physical Chemistry, 35, 357-385. 

The book covers a gamut of related topics such as methods for determining atoms-in-molecuies, population analysis, electrostatic potential, molecular quantum similarity, aromaticity, and biological activity. It also discusses the role of reactivity concepts in industrial and other practical applications. Whether you are searching for new products or new research projects, this is the ultimate guide for understanding chemical reactivity. 

Jiali Gao, Methods and Applications of Combined Quantum Mechanical and Molecular Mechanical Potentials. 

The applications of NN to solvent extraction, reported in section 16.4.6.2., suffer from an essential limitation in that they do not apply to processes of quantum nature therefore they are not able to describe metal complexes in extraction systems on the microscopic level. In fact, the networks can describe only the pure state of simplest quantum systems, without superposition of states. Neural networks that indirectly take into account quantum effects have already been applied to chemical problems. For example, the combination of quantum mechanical molecular electrostatic potential surfaces with neural networks makes it possible to predict the bonding energy for bioactive molecules with enzyme targets. Computational NN were employed to identify the quantum mechanical features of the... 

This chapter has emphasized the special and central role that feedback plays in virtually all aspects of control over molecular quantum phenomena. In terms of applications, the manipulation of chemical reactions still stands as a prime historical objective. However, other rich applications abound. For example, the growing interest in the field of quantum computing is a potentially exciting area [14], and any practical realization of quantum computers will surely entail control over quantum phenomena. Other unforeseen applications may also lie ahead. 

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