title: Theoretical Investigation of Molecular and Electronic Structures of Buckminsterfullerene-Silicon Quantum Dot Systems.
abstract: Density functional theory (DFT) and density functional tight binding (DFTB) molecular dynamics (DFTB/MD) simulations of embedding and relaxation of buckminsterfullerene C60molecules chemisorbed on (001) and (111) surfaces and inside bulk silicon lattice were performed. DFT calculations of chemisorbed fullerenes on both surfaces show that the C60molecule deformation was very small and the C60binding energies were roughly ∼4 eV. The charge analysis shows that the C60molecule charges on (001) and (111) surfaces were between -2 and -3.5 electrons, respectively, that correlates well with the number of C-Si bonds linking the fullerene molecule and the silicon surface. DFT calculations of the C60molecule inside bulk silicon confirm that the C60molecule remains stable with the deformation energy values of between 11 and 15 eV for geometries with different C60configurations. The formation of some C-Si bonds causes local silicon amorphization and corresponding electronic charge uptake on the embedded fullerene cages. Charge analysis confirms that a single C60molecule can accept up to 20 excessive electrons that can be used in practice, wherein the main charge contribution is located on the fullerene's carbon atoms bonded to silicon atoms. These DFT calculations correlate well with DFTB/MD simulations of the embedding process. In this process, the C60molecule was placed on the top of the Si(111) surface, and it was further exposed by a stream of silicon dimers, resulting in subsequent overgrowth by silicon.
authors.affiliation: Kirensky Institute of Physics, Federal Research Center KSC, Siberian Branch RAS , 660036 Krasnoyarsk, Russia.|Siberian Federal University , 79 Svobodny Prospect, 660041 Krasnoyarsk, Russia.
authors.forename: A S
authors.identifier: http://orcid.org/0000-0002-7911-3301
authors.initials: AS
authors.lastname: Fedorov
authors.affiliation: Kirensky Institute of Physics, Federal Research Center KSC, Siberian Branch RAS , 660036 Krasnoyarsk, Russia.|Siberian Federal University , 79 Svobodny Prospect, 660041 Krasnoyarsk, Russia.
authors.forename: A A
authors.initials: AA
authors.lastname: Kuzubov
authors.affiliation: Siberian Federal University , 79 Svobodny Prospect, 660041 Krasnoyarsk, Russia.
authors.forename: A S
authors.initials: AS
authors.lastname: Kholtobina
authors.affiliation: Siberian Federal University , 79 Svobodny Prospect, 660041 Krasnoyarsk, Russia.
authors.forename: E A
authors.initials: EA
authors.lastname: Kovaleva
authors.affiliation: Bremen Center for Cormputational Materials Science, University of Bremen , 28359 Bremen, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Knaup
authors.affiliation: Institute of Transformative Bio-Molecules (WPI-ITbM) & Department of Chemistry, Graduate School of Science, Nagoya University , Nagoya 464-8602, Japan.
authors.forename: S
authors.identifier: http://orcid.org/0000-0003-4995-4991
authors.initials: S
authors.lastname: Irle