Journal ArticleDOI
Graph-theoretical method for evaluation of eigenvalues of real symmetric matrices from an eigenvector approach
Reads0
Chats0
TLDR
In this paper, it was shown that for any two topologically similar vertices i and k, A2ji=A2jk; for all j≠k and i where Aji is the cofactor of the (j,i) element of the secular determinant det(xI-A), A is the adjacency matrix of the graph G and I is the (n×n) unit matrix.Abstract:
It has been proved that if {vi}, i= 1–n, is the set of vertices of an undirected labelled graph G, then for any two topologically similar vertices i and k, A2ji=A2jk; for all j≠k and i where Aji is the cofactor of the (j,i) element of the secular determinant det(xI–A), A is the adjacency matrix of the graph G and I is the (n×n) unit matrix.As any real symmetric matrix, A, can be represented by an undirected vertex- and edge-weighted graph (G), the above relation has been utilised, in conjunction with a recently developed graph-theoretical method for expressing eigenvectors of A as polynomials in terms of eigenvalues, to determine a good number of eigenvalues of the matrix. The method, for the first time, utilises a newly developed technique of determination of eigenvectors for evaluation of eigenvalues. In one particular case it has been shown that the present method can reduce the required polynomial equations to a degree lower than that possible by McClelland's technique for factorisation of chemical graphs. Some applications of the method (other than HMO theory), for example, calculation of principal stress tensors in fluid dynamics and force constants in a molecular vibration problem, are illustrated.read more
Citations
More filters
Journal ArticleDOI
Graphic rules for reducing the order of the Hückel determinant
TL;DR: McClelland's rules are generalized to construct characteristic polynomials of molecular graphs with a symmetry plane, and a new graphic representation of the adjacency matrix is suggested.
References
More filters
Journal ArticleDOI
General rules for constructing Hueckel molecular orbital characteristic polynomials
Journal ArticleDOI
Graphical method for factorizing secular determinants of Hückel molecular orbital theory
TL;DR: In this paper, a graphical method for simplifying the solution of Huckel's secular equations for molecules with symmetrically-placed atoms is presented, where the solution can be expressed as follows:
Journal ArticleDOI
Quantum Mechanics of Mobile Electrons in Conjugated Bond Systems. III. Topological Matrix as Generatrix of Bond Orders
TL;DR: In this article, it was shown that in homonuclear conjugated systems the various bond orders and similar quantities can be written as matrix functions of the topological incidence matrix.
Journal ArticleDOI
On the eigenvalues of molecular graphs
TL;DR: In this article, it is shown that for alternants which possess a two-fold symmetry operation, the eigenvalues must have certain relationships, which explain why certain eigen values occur frequently in the spectra of different molecules.