INDEX atomic

The 5 connectivity index (atom degree), that has a central role in computing the E-state, was used in the definihon of the Zagreb topological indices [11]. Randle modified the Zagreb index M2 to obtain the connectivity index % [12]. 

Other information indices are - atomic composition indices, - information bond index, -> Morowitz information index, information index on size, information index on molecular symmetry, - information index on amino acid composition, -> information index on molecular conformations, -> Bertz complexity index, - Dos-morov complexity index, - Bonchev complexity index, -> atomic information indices, and electropy index. 

The summation is over the A atoms of the skeleton. The zero order chi index carries a low level of structure information. Little of the connectedness of the skeletal network is encoded only the fact of the presence of the nearest neighbor to each atom is encoded. In the °X index, atom identities are quantitated. 

Pattern (I.l) may be simplified in different ways we can omit the circles and leave only dots at A, B, C, and D. Sometimes the reacting (index) atoms are put into a frame. The most concise way is to show only the atoms and bonds of the index group set in such a manner that during the reaction two vertical bonds (where the plane of the paper corresponds to the surface of the catalyst) are broken and two horizontal ones arise. Then the pattern (I.l) as a whole can be represented in the form of an index ... 

In the enzymic catalysis not only the index atoms must come into contact with the catalyst, but their extra-index substituents as well. The structural correspondence must be still more precise, which explains the high selectivity of enzymes (see Section 1,1). With some alternations the same refers to the antimetabolites (Section 1,1) and seemingly to antibodies (17). There exists a theory of scents which uses the principle of structural correspondence. Recently, the principle of structural correspondence was also used to explain the dependence of the physiological action of anesthetics upon the structure of the molecules (18). 

If the index atoms are not attached to the catalyst simultaneous-hq in the case of too strong a deformation of bonds the free radicals formed can migrate from one valley to another if the activation barriers of migration are not too high. The migration of radicals may give rise to surface chain reactions. The latter will be particularly possible in the case of more stable free radicals, for instance, the methylene radical >CH2 (see Section I,E). 

In Eqs. (1.16) a complete break of bonds is assumed, which is an extreme case, however. The getting of index atoms into a deeper valley L (Fig. 6) corresponds to activated adsorption. The model of Fig. 6 satisfies the princijile of the conservation of valence angle (see p. 31). It permits one to employ a computation according to the theory of absolute reaction rates and conveys well enough different features of the theory of hydrogenation, based on the multiplet theory (78-83). 

Enzymes are known to operate at low temperatures and this favors the arrangement of lateral extra-index substituents of the substrates in parallel with the surface. One should remember that it was at lower temperatures that an adsorption parallel to the surface was observed. Therefore the substituents are attracted to the surface near the active centers, on which the reacting index atoms are superimposed. 

One possible approach to the study of chemical reactivity is to determine the degree that the atoms in a molecule are bonded to adjacent atoms relative to their theoretical maximum bonding power. If particular atoms are not much bonded compared to the maximum, we could say that they have considerable "free valence" and especially reactive positions. Coulson defines a free valence index, atom i as follows ... 

Coverage 6i, for which AO is determined sometimes 0i marks a relative coverage for which extrema of the AO variation occur ML stands for monolayer. A coverage notation 6index is defined as the number ratio of adsorbed index atoms and substrate surface atoms. 

---