HMO characteristic polynomial and select eigenvalues for many heterocyclic benzenoids are calculated by using chemical graph theory methods.
The formulae for the number of loops, edges, triangles, pairs of two-way nodes and pairs of one-way nodes are deduced by the coefficients of a characteristic polynomial, so on.
In this paper, we present an iterative method for determining whether all roots of characteristic polynomial are on the left half-plane.
