topological analysis and quantum mechanical structure of c4 and c5 pure carbon clusters

two bonding models i.e cumullenic and acetylenic models have been proposed to account for thebonding patterns in linear carbon clusters while the bonding patterns in cyclic and 3d geometries of theseclusters have remained ambiguous.this work presents the bonding patterns in various c4 and c5 pure clusters at mp2/aug-cc-pvtz level oftheory. this subject is studied in the light of modern bonding theory known as quantum theory ofatoms in molecules, qtaim.in linear clusters the ethylene like chemical bonds are reported, while in cyclic and 3d geometries thesingle and triple c-c bonds are found.