title: Chemical sub-structural cluster expansions for molecular properties.
abstract: Abstract   The correlation of different molecular sub-structures with various molecular properties has a long history, of over a century. And currently such structural characterizations still remain of central interest in chemistry. Thus a general formalism to analyze a property or activity in terms of sub-structural contributions is of interest, and is pursued here. The approach may indeed be viewed as a formalization and extension of standard bond-energy ideas as arise even in introductory chemistry courses. The present formalism allows for:   • a more complete and comprehensive formulation, with higher-order corrections to achieve greater accuracy;   • a more general form for the class of sub-structures appearing in the expansion, thereby allowing more general (e.g., "multiplicative") properties to be expanded; and   • a more general form for the expansion functions, thereby allowing more rapid convergence rates for the expansions.   An illustrative example for the structure/property correlation of conjugated-hydrocarbon π-energy is made. Some comments on the use for describing bio-activities, and in particular toxicities, are made.
authors.affiliation: a    Texas A & M University at Galveston   ,  Galveston ,  Texas ,  77553-1675 ,    USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Klein
authors.forename: T G
authors.initials: TG
authors.lastname: Schmalz
authors.forename: L
authors.initials: L
authors.lastname: Bytautas