2017. 58, 1 UDC 541.6:547.12 A THEORETICAL STUDY OF THE SOLVENT EFFECT ON THE INTERACTION OF C20 AND N2H2 H. Alavi1, R. Ghiasi2 1Department of Chemistry, Kerman Branch, Islamic Azad University, Kerman, Iran 2Department of Chemistry, East Tehran Branch, Tehran, Islamic Azad University, Qiam Dasht, Iran E-mail: rezaghiasi1353@yahoo.com, rghiasi@iauet.ac.ir Received July, 1, 2015 In this work, the interaction of C20 and the N2H2 fragment is investigated at the M062X/6311G(d,p) level of theory in both gas and solution phases. <...> The interaction energies obtained by the standard method are corrected by the basis set superposition error (BSSE) during the geometry optimization for all molecules at the same levels of theory. <...> The results obtained from these calculations reveal that the interaction between C20 and N2H2 increases in the presence of more polar solvents. <...> Values of the electrophilic charge transfer show the charge flow from C20 to N2H2. <...> The influence of the solvent on the hyperpolarizability indicates that itot values decrease on passing from vacuum to the solution phase. <...> INTRODUCTION The structure and properties of a C20 molecule have been investigated theoretically and experimentally [ 1—6]. <...> This molecule is potentially the smallest fullerene. <...> The synthesis and characterization of this molecule has been reported in the gas phase [ 7 ]. <...> The remarkable structure of C20 has been the question of numerous theoretical researches [ 8, 9]. <...> The structure and properties of fullerene C20 and its derivatives C20(C2H2)n and C20(C2H4)n (n = 1—4) have been explored [ 12 ], and they illustrate that the most stable fullerene C20 and its derivatives C20(C2H2)n and C20(C2H4)n (n = 1—3) exhibit significant aromaticity, while C20(C2H2)4 and C20(C2H4)4 have no spherical aromaticity. <...> Furthermore, heteroatom impacts on the structure, stability, and aromaticity of XnC20–n fullerenes have been established [ 13 ]. <...> The structure, aromaticity, frontier orbital analysis, and the natural bond analysis of C20…N2X2 molecules have been explored, and the influence of the basis set and methods on the structure and interaction energies of these molecules have been investigated. <...> The presence of specific and non-specific interactions between the solvent and the solute molecules is responsible for the change in several properties such as the molecular geometry <...>