Molecular geometry INDEX

Here /, are the three moments of inertia. The symmetry index a is the order of the rotational subgroup in the molecular point group (i.e. the number of proper symmetry operations), for H2O it is 2, for NH3 it is 3, for benzene it is 12 etc. The rotational partition function requires only information about the atomic masses and positions (eq. (12.14)), i.e. the molecular geometry. 

It was mentioned earlier that a number of special purpose routines, which do not appear in the VPLIB index, have been developed for use in structural chemistry. The most frequent requirements encountered in this area are those concerned with molecular geometry and, more specifically, with the calculation of interatomic distances, angles and torsion angles. These geometric quantities are best evaluated by vector algebra and this will always involve the calculation of vector components, lengths, direction cosines, vector cross products and vector dot products. Attention should therefore be directed at the best possible way of implementing the calculations described in the latter list on the MVP-9500. 

From the geometry matrix, the usual -> graph invariants can be calculated such as -t characteristic polynomial, -> eigenvalue-based descriptors, -> path counts, - ID numbers, -> 3D-Balaban index, -> 3D-Schultz index and so forth [Randic, 1988b Nikolic et al, 1991]. It is noteworthy that all these indices are sensitive to molecular geometry. Moreover, the geometry matrix is used for the calculation of size descriptors and - 3D-MoRSE descriptors. 

Klopman G, Dimayuga ML. Computer Automated Structure Evaluation (CASE) of the teratogenicity of retinoids with the aid of a novel geometry index. Journal of Computer-Aided Molecular Design. 1990 4(2) 117-130. 

Based on the idea that bond alternation causes the aromatic character to decrease, the first aromaticity index based on the —> molecular geometry was proposed by Julg and Frangois [ Julg and Franfois, 1967] as... 

Note. The authors called this index as topological, although it depends on the molecular geometry. 

The multivariate correlation index calculated by diagonalization of the WHIM we hted covariance matrices derived from —> molecular geometry is also among the WHIM shape descriptors. 

The CS INDO program [1,2], modified by the incorporation of the solute-solvent interaction as described in section 2.1, was used to calculate molecular geometries, charge distributions and electronic absorption spectra of the merocyanines M1-M3 (Fig. 1) as a function of the solvent polarity index. ... 

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