π-Electron currents in fully aromatic benzenoids

National Institute of Chemistry, P.O. Box 3430, 1001 Ljubljana, Slovenia
E-mail: mrandic@msn.com
Ruaer Boskovic Institute, NMR Center, P.O. Box 180, HR-10002 Zagreb, Croatia
E-mail : dplavsic@irb.hr
Department of Mathematics, Faculty of Natural Sciences and Mathematics, University of Split, Nikole Tesle 12, HR-21000 Split, Croatia
E-mail : vukicevi@pmfst.hr
Manuscript received 21 October 2010, accepted 29 October 2010

In view of different patterns of π-electron density currents. reported by ab initio calculations for cata- and peri-condensed compounds, we consider π-electron currents of fully benzenoid cata-condensed tetrabenzoanthracene and peri-condensed dibenzopyrene in order to discern the pattern of ring currents in fully benzenoid hydrocarbons, rings of which have either π-sextets or are "empty" in the terminology of Clar. Our graph theoretical calculations of π-electron currents is based on calculations of contributions from conjugated circuits of individual Kekulé valence structures of these molecules.