STORING OF MOLECULAR HYDROGEN IN GRAPHITE CELL. AN AB INITIO STUDY.

A. Bende1,2

1National Institute for Research and Development of Isotopic and Molecular Technologies, 71-103 Donath, RO 400293 Cluj-Napoca, Romania.
2Molecular Biophysics Department, German Cancer Research Center, Im Neuenheimer Feld 580, D-69120, Heidelberg, Germany.

	Weakly-bounded hydrogen bonds are of fundamental importance in structural chemistry and biology, supramolecular chemistry and crystal engineering. Molecular hydrogen (H2) holds a promise of the ideal energy source for production of electricity in transportable devices. Carbon-based materials, such as nano-structurated graphite platelets (graphene) or cells are among the most attractive physisorption substrates. A computationally tractable model of graphene is provided by polycyclic aromatic hydrocarbons (PAH’s) such as benzene. The importance of benzene and molecular hydrogen complex as model system for molecular hydrogen storage in graphite cells as well as the importance of noncovalent interactions in a variety of different systems prompted us to study the H2…π interaction. Adequate quantum-chemical description of H2-PAH interactions require post-Hartree-Fock treatment of electron correlation and of basis set superposition error (BSSE) effects. In our previous study [1] we analyzed the weakly-bounded hydrogen bonds between acetylene and different proton donors as a model of  C-H…π interaction. Important BSSE effects have been found due to the long range interaction of electron correlation, especially for the dispersion energy component. Similar effects can be found in case of benzene and molecular hydrogen complex. To treat this effect, we use the well-known a posteriori counterpoise (CP) BSSE correction scheme introduced by Boys and Bernardi [2]. The theoretical values of interaction energies between the benzene ring and the molecular hydrogen as well as the intermolecular distances between them show an important BSSE and basis size effects.

Reference:

1.	A. Bende, Á. Vibók, G. J. Halász, and S. Suhai: “Theoretical study of Hydrogen Bonds between Acetylene and Selected Proton Donors”, International Journal of Quantum Chemistry, 101, 186-200 (2005). 
2.	S. B. Boys, and F. Bernardi, Molecular Physics, 19, 553 (1970).