An efficient algorithm leading to the Fries canonical structure is presented for benzenoid hydrocarbons. This is a purely topological approach, which is based on adjacency matrices and the Hadamard procedure of matrix multiplication. The idea is presented for naphthalene, as an example. The Fries canonical-structures are also derived for anthracene, coronene, triphenylene, phenanthrene, benz[a]...

The local aromaticity of a series of benzenoid systems was determined through the use of structurally (HOMA) and magnetically (NICS) based measures, and also by using a new electronically based indicator of aromaticity, the para-delocalization index (PDI). The results were compared with the predictions of Clar’s aromatic -sextet rule. It is found that, for all analyzed benzenoid hydrocarbons ha...

The "perturbation" effects (i.e. hyperconjugation, electronegativity, and conjugation) on the structural, electronic, and magnetic properties of three kinds of two-dimensional (2D) X-Cr-X (X = C4H, NC3 and BC3 monolayers) sandwich nanostructures were systematically investigated by means of spin-polarized density functional theory (DFT) computations. Although all these 2D sandwich systems energe...

G. Clar 6n Rule versus Hückel 4n + 2 Rule 3464 H. Hydrocarbons versus Heteroatomic Systems 3465 IV. Hidden Treasures of Kekulé Valence Structures 3466 A. Conjugated Circuits 3467 B. Innate Degree of Freedom 3470 C. Clar Structures 3472 V. Graph Theoretical Approach to Chemical Structure 3473 A. Metric 3473 B. Chemical Graphs 3473 C. Isospectral Graphs 3473 D. Embedded Graphs 3475 E. Partial Ord...

A reference catalogue of 1274 fully-resonant azulenoid tiling patterns with a symmetry group that operates transitively on the azulenes has been generated, and may be consulted at http://caagt.ugent.be/azul. Such networks are analogous to Clar structures and fully-naphthalenoid structures among benzenoids.

" Clarithmetic " is a generic name for formal number theories similar to Peano arithmetic, but based on computability logic instead of the more traditional classical or intuitionistic logics. Formulas of clar-ithmetical theories represent interactive computational problems, and their " truth " is understood as existence of an algorithmic solution. Imposing various complexity constraints on such...

As a strengthening of the concept global forcing number graph G, complete G is cardinality minimum edge subset to which restriction every perfect matching M set M. Xu et al. (J Comb Opt 29: 803–814, 2015) revealed that also antifores each matching, and obtained for catacondensed hexagonal system, equal Clar plus hexagons (Chan MATCH Commun Math Comput Chem 74: 201–216, 2015). In this paper, we ...