Mozhgan Sabzehzari - Department of Chemistry, Basic Science College, Jundi shapur University of Technology-Dezful

The smallest possible of these polycyclic diamondoids is adamantine (C6H12) with uniquephysical and chemical properties. DFT calculations for adamantine show that they are nonreactive,and interact weakly with each other [1]. Substituting H and C-H groups with differentatoms and functional groups like N, Na, B and O atoms changes its electronic properties such as,the HOMO-LUMO gap, conductance and binding energy [2,3]. The Si or Ge small cagedmolecules are unstable in pristine configurations, since the respective atoms strongly favor thesp3 -like bonding over the sp2 -like one, and molecules tend to stabilize in more compact forms.In this paper, we have doped one to ten carbon atoms of adamantine with Ge atoms andinvestigated their structure and electronic properties using density functional theory. Ourcalculations are based on the ab initio density functional theory (DFT) within three parameterM06/6-31+G** functional. The natural bond orbital (NBO) calculations and all calculations ofHOMO-LUMO gaps were also performed at the same level of theory. Gaussian09 package wasused for all calculations. we obtained the optimized structure 1-10 germa- adamantine with theirisosurfaces plot of HOMO and LUMO states. Doping with germanium atoms lowers the energygap in most structures. Any way 6-Germa adamantane show the highest energy gap among allstructures.

Adamantane, ab initio density functional theory (DFT), energy gap, Electronic Properties