Ideas of Quantum Chemistry P85 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. | 806 14. Intermolecular Motion of Electrons and Nuclei Chemical Reactions Kenichi Fukui 1918-1998 Japanese chemist professor at the Kyoto University. One of the first scholars who stressed the importance of the IRC and introduced what is called the frontier orbitals mainly HOMO and LUMO which govern practically all chemical processes. Fukui received the Nobel Prize in chemistry in 1981. Now instead of Al 0 let us take two doubly excited configurations of the total system 58 l 2d N2 1 p 1 3 P3 and 3d N3 2 P2 3 P3 where Ni stand for the normalization coefficients. Let us ask about the coeffi- cients that they produce for the DA configuration let us call these coefficients C2 DA for l 2d and C3 DA for . I 2 GUVI da C2 D A d a- 1 3 3 D V I da C3 D A d a- . According to the result described above see p. 1058 we obtain C2 DA C3 DA a1 b1 2 -a3 b3 a2 -b2 -a3 b3 a1b3 3 b1 2 2 2b3 - 3b2 2. Such formulae enable us to calculate the contributions of the particular donoracceptor resonance structures . DA D A- etc. cf. p. 520 in the Slater determinants built of the molecular orbitals of the total system. If one of these structures prevailed at a given stage of the reaction this would represent important information about what has happened in the course of the reaction. Please recall that at every reaction stage the main object of interest will be the ground-state of the system. The ground-state will be dominated59 by various resonance structures. As usual the resonance structures are associated with the corresponding chemical structural formulae with the proper chemical bond pattern. If at a reaction stage a particular structure dominated then we would say that the system is characterized by the corresponding chemical bond pattern. REACTION STAGES We would like to know the a b c values at various reaction stages because we could then calculate the coefficients C0 C2 and C3 for the DA as well as for other donor-acceptor .
