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Ideas of Quantum Chemistry P110

Ideas of Quantum Chemistry P110 shows how quantum mechanics is applied to chemistry to give it a theoretical foundation. The structure of the book (a TREE-form) emphasizes the logical relationships between various topics, facts and methods. It shows the reader which parts of the text are needed for understanding specific aspects of the subject matter. Interspersed throughout the text are short biographies of key scientists and their contributions to the development of the field. | 1056 Y. PAULI DEFORMATION Fig. Y.2. The locality of the Pauli deformation diagram . a Two polymeric chains A and B with electronic densities in the form of the elongated rectangles corresponding to the isolated molecules A and B approach one another b the Pauli deformation consists of the two density gains the rectangles with and a single electron loss the rectangles with . Let us assume that the surfaces of the rectangles are equal to the corresponding integrals of the charge distributions 4S 1 S2 ab in the contact region 2S2 1 S2 a2 on molecule A and 2S2 1 S2 b2 on polymer B - this is why the electron density loss has a rectangle twice as large as any of the electron density gains c a partial Pauli deformation the density gain 2S2 1 S2 a2 for molecule A has been added to the initial density distribution and similarly for molecule B the rectangles became larger but locally the corresponding increase is small . d In order to represent the total Pauli deformation from the result obtained at point cwe subtracted the density distribution 4S 1 S2 ab which is located in the contact region. As a result the Pauli deformation when viewed locally is large only in the contact region. The only thing that has been changed with respect to the hydrogen molecule is the increase in the number of electrons from two to four we have kept the orbital exponents equal to 1 and the internuclear distance equal to 4 a.u. unchanged . This change results in a qualitative difference in the Pauli deformation. Two large molecules For two helium atoms the Pauli deformation means decreasing the electron density in the region between the nuclei and a corresponding increase in the density on the nuclei. This looks dangerous What if instead of two helium atoms we have two closed-shell long molecules A and B that touch each other with their terminal parts Would the Pauli deformation be local or would it extend over the whole system Maybe the distant parts of the molecules would deform as much as the