Mathematical formalism, constants structure

Of course, Eq. (1) is only a mathematical formalism. Whereas biological activities can easily be defined by a certain endpoint (e.g., an effective dose, a 50% inhibition constant, a 100% lethal dose, etc.), it was and still is impossible to describe chemical structures in an absolute manner. Only changes in biological activities A

chemical structures AC (Eq. (2)). Such chemical changes can be quantified either by structural terms (indicator variables, dummy variables, Free-Wilson parameters) or by the resulting change in various physicochemical or other properties ... 

Quantum chemistry is the fundamental theory of molecules it allows for an all embracing and correct description ofthe structure and properties of single molecules. In principle all experimentally measurable properties could be calculated mathematically by applying the quantum chemical formalism thereby the only empirical parameters are the Planck constant, the velocity oflight, the masses, the spins and the electromagnetic momentum of the electron and of the nuclei (Muller-Herold and Primas 1984, 309). 

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