| Abstract: | The communication channels of the disconnected (mutually non-bonded, closed) parts of the molecule are investigated. The entropy/information indices of such subsystems are proposed as measures of the intra-fragment (internal) information bond-order and its covalent/ionic components. The molecular fragment bond-order conservation and a competition between its ionic and covalent contributions are examined. An approximate scheme in the spirit of the grouping theorem of the Information Theory (IT), for combining the subsystem entropy/information data into the corresponding global quantities describing the system as a whole, is derived and tested. It uses the independent subsystem approximation to estimate the entropy/information indices of the inter-fragment (external) chemical interactions in the molecule. The applications to simple orbital models, including the three-orbital model of the transition state complex and the π bond systems (butadiene and benzene) in the Hückel theory approximation, are used to illustrate the concepts proposed. |
