The Unrestricted Hartree-Fock Theory of Chemical Reactions. I: The Electronic Instabilities in the Chemical Reactions and the Solutions of the Unrestricted SCF LCAO MO Equation for the Homopolar Two-Center Two-Electron System
The Unrestricted Hartree-Fock Theory of Chemical Reactions. I: The Electronic Instabilities in the Chemical Reactions and the Solutions of the Unrestricted SCF LCAO MO Equation for the Homopolar Two-Center Two-Electron System
复制标题
无限制的哈特里-福克化学反应理论。
DOI：
10.1143/ptp.47.1156
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发表时间：
1972
影响因子：
--
通讯作者：
H. Fukutome
中科院分区：
文献类型：
--
作者：
H. Fukutome
It is shown that the conventional closed shell type ground state solution of SCF LCAO MO equation, which satisfies the requirement of the symmetry, may become unstable in the course of chemical reactions. The instability of the conventional SCF ground state in the chemical reactions, is indicated for the dissociation reaction of a hydrogen molecule, the in ternal rotation of an ethylene, the exchange reaction of two hydrogen molecules and the cyclic addition reaction of two ethylenes. The occurrence of the electronic instability in a wide class of chemical reaction forces to use the unrestricted SCF theory in which the re strictions for the spin state and the. symmetry requirement of the orbitals are removed. As the simplest example of the unrestricted SCF MO theory of chemical reactions, the solutions of the unrestricted SCF LCAO MO equation for the homopolar two-center two-electron sys tem are discussed. The unrestricted SCF equation provides two new kinds of solutions with broken symmetry. The one is the solution of spin density wave type and it correctly ap proximates the true ground state in the region where the conventional ground state solution becomes unstable. The other is the solution of charge density wave type and it correctly approximates the true doubly excited state, where the conventional doubly excited configura tion departs from the correct behavior. The implications of the occurrence of the instability and the appearance of the broken symmetry SCF states in chemical reactions are discussed.
