The Electropy Index

FHaya et al. 89) introduced an information index e, called electropy, based on the assumption that the molecule forms a finite space which is divided into several partial bond spaces according to the electronic pairings in the molecule. The electropy, e, is viewed as a measure of the degree of freedom of choice for electrons in occupying different partial spaces in during the process of molecular formation. 

The calculation of electropy is carried out according to the equation of information theory 73) used in cases of equal probabilities of the possible events P0 and 

A correction term to electropy is introduced which takes into account the effect of steric hindrance between adjacent methyl groups connected to the t-th carbon atom  

The combination of the electronic and topological factors within this approach yields high correlations with thermodynamic properties of molecules. 

Through the I Haya electropy was meant as an electronic information index, it is essentially topological in nature, but takes also into account electronic and steric factors through the intermediacy of topology. 

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The electropy index may be viewed as a measure of the degree of freedom for electrons to occupy different subspaces during the process of molecular formation. 

Mekenyan, O., Bonchev, D., Sabljic, A. and Trinajstic, N. (1987). Applications of Topological Indices to QSAR. The Use of the Balaban Index and the Electropy Index for Correlations with Toxicity of Ethers on Mice. Acta Pharm.Jugosl.,37,75-86. 

Information-theoretic indices, including the Shannon index, the chromatic information index, the orbital information index, the topological information superindex, the electropy index, and the Merrifield and Sinmions indices [13,14]. 

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