tailieunhanh - Ideas of Quantum Chemistry P51

Ideas of Quantum Chemistry P51 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. | 466 9. Electronic Motion in the Mean Field Periodic Systems monomer polymer Fig. . Rationalizing the band structure of polyparaphenylene n-bands . The COs in centre built as in-phase or out-of-phase combinations of the benzene n molecular orbitals left-hand side . It is seen that energy of the COs for k 0 and k n agree with the rule of increasing number of nodes. A small band width corresponds to small overlap integrals of the monomer orbitals. . André J. Delhalle . Brédas Quantum Chemistry Aided Design of Organic Polymers World Scientific Singapore 1991. Reprinted with permission from the World Scientific Publishing Co. Courtesy of the authors. A stack of Pt II square planar complexes Let us try to predict40 qualitatively without making calculations the band structure of a stack of platinum square planar complexes typically Pt CN- 2- œ. Con 40R. Hoffmann Solids and Surfaces. A Chemist s View of Bonding in Extended Structures VCH Publishers New York 1988. Solid state quantum chemistry 467 sider the eclipsed configuration of all the monomeric units. Let us first simplify our task. Who likes cyanides Let us throw them away and take something theoreticians really love is a little less than just laziness. If needed we are able to make calculations for cyanides too but to demonstrate that we really understand the machinery we are always recommended to make the system as simple as possible but not simpler . We suspect that the main role of CN- is just to interact electrostatically and H- does this too being much smaller . The electronic dominant configuration of the platinum atom in its ground state is41 Xe 4f 14 5d96s1 see the Mendeleev Table in the Web Annex . As we can see we have the xenon-like closed shell and also the full closed subshell 4f. The orbital energies corresponding to these closed shells are much lower than the orbital energy of the hydrogen anion they are to be combined to . This is why they will not participate in the Pt-H .