2013. 54, 5 UDC 541.6:548.737 ADSORPTION BEHAVIOR OF CO AND C2H2 ON THE GRAPHITE BASAL SURFACE: A QUANTUM CHEMISTRY STUDY T. Hosseinnejad1, R. Abdullah Mirzaei2, F. Nazari2, M.H. Karimi-Jafari3 1Department of Chemistry, Faculty of Science, Alzahra University, Vanak, Tehran, Iran E-mail: tayebeh.hosseinnejad@alzahra.ac.ir Received April, 9, 2012 2Department of Chemistry, Faculty of Science, Shahid Rajaee Teacher Training University, Tehran, Iran 3Institute of Biochemistry and Biophysics, University of Tehran, Iran Revised — July, 29, 2012 The adsorption of CO and C2H2 molecules on the perfect basal surface of graphite is investigated by adopting cluster models in conjunction with quantum chemical calculations. <...> The noncovalent interaction potential energy curves for three different orientations of CO and C2H2 molecules with respect to the inert basal plane of graphite are calculated via semi-empirical and Mцller-Plesset ab initio methods. <...> Then, we have considered the effects of interaction energies on the CO and CC bond lengths by performing the partial geometry optimization procedure on the CO-graphite and C2H2-graphite systems in various intermolecular distances. <...> The computational analysis of all physical noncovalent potential energy curves reveals that the relative configurations in which CO and C2H2 molecules approach the graphite sheet from out of the plane have stronger interaction energy and so is more favorable from the energetic viewpoint. <...> This means that the graphite layer prefers to increase its thickness via the chemical vapor deposition of CO and C2H2 on the graphite. <...> Keywords: graphite basal surface, carbon monoxide, acetylene, physical interaction energy, quantum chemical calculations. <...> One of the most important methods of producing carbon materials is chemical vapor deposition (CVD) on graphite surface. <...> In the recent years much attention to the growth of carbon materials, such as carbon fibers, carbon nanotubes [ 1, 2 ], pyrolytic carbons [ 3, 4 ], and carbon nanospheres (that are all related mainly to graphite structures) by performing the catalytic CVD procedure. <...> In this technique, carbon monoxide and acetylene are widely used as appropriate substrates. <...> It should be stated that the extended honeycomb structure model of graphite surface is the basic building block of other important allotropes such as 3D <...>