An algorithm and FORTRAN program for automatic computation of the Zhang-Zhang polynomial of Benzenoids

Abstract

An automatic computer code is developed to calculate the Zhang–Zhang (ZZ) polynomial (aka Clar covering polynomial) for benzenoid systems. The code can be routinely applied to dense pericondensed benzenoids containing up to 500 carbon atoms. For catacondensed and quasi-linear pericondensed benzenoid systems, the limiting number of atoms is much larger and may exceed 10000. A parallel implementation of the code is also presented, which allows one to surpass these limits with a large number of CPUs. The developed program is applied for finding the ZZ polynomials of various classes of benzenoid systems; general techniques and algorithms applicable in this context are reviewed and discussed. A survey of new results obtained in that way is presented in a sequel to this paper [C.-P. Chou, Y. Li, and H.A. Witek, MATCH Commun. Math. Comput. Chem., submitted].