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Phys. Rev. B 73, 035109 (2006) [9 pages]

Electronic structure and vibrational spectra of C2B10-based clusters and films

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Kyungwha Park1,2,*, M. R. Pederson1, and L. L. Boyer1,†
1Center for Computational Materials Science, Naval Research Laboratory, Washington D.C. 20375-5345, USA
2Department of Physics, Georgetown University, Laboratory, Washington D.C. 20007, USA

W. N. Mei3 and R. F. Sabirianov3
3Department of Physics, University of Nebraska at Omaha, Omaha, Nebraska 68182, USA

X. C. Zeng4 and S. Bulusu4
4Department of Chemistry, University of Nebraska at Lincoln, Lincoln, Nebraska 68588, USA

Seamus Curran5 and James Dewald5
5Department of Physics, New Mexico State University Las Cruces, New Mexico 88003, USA

Ellen Day6
6Department of Mechanical Engineering, University of Nebraska at Lincoln, Lincoln, Nebraska 68588, USA

Shireen Adenwalla7, Manuel Diaz7, Luis G. Rosa7, S. Balaz7, and P. A. Dowben7
7Department of Physics, University of Nebraska at Lincoln, Lincoln, Nebraska 68588, USA

Received 15 July 2005; revised 2 November 2005; published 9 January 2006

The electronic structure, total energy, and vibrational properties of C2B10H12 (carborane) molecules and C2B10 clusters formed when the hydrogen atoms are removed from carborane molecules are studied using density functional methods and a semiempirical model. Computed vibrational spectra for carborane molecules are shown to be in close agreement with previously published measured spectra taken on carborane solids. Semiconducting boron carbide films are prepared by removing hydrogen from the three polytypes of C2B10H12 deposited on various surfaces. Results from x-ray and Raman scattering measurements on these films are reported. Eleven vibrationally stable structures for C2B10 clusters are described and their energies and highest occupied and lowest unoccupied molecular orbital gaps tabulated. Calculated Raman and infrared spectra are reported for the six lowest-energy clusters. Good agreement with the experimental Raman spectra is achieved from theoretical spectra computed using a Boltzmann distribution of the six lowest-energy free clusters. The agreement is further improved if the computed frequencies are scaled by a factor of 0.94, a descrepancy which could easily arise from comparing results of two different systems: zero-temperature free clusters and room-temperature films. Calculated energies for removal of hydrogen pairs from carborane molecules are reported.

© 2006 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevB.73.035109
DOI:
10.1103/PhysRevB.73.035109
PACS:
78.30.−j, 31.15.Ew, 36.40.Qv, 81.05.Hd

*Current address: Department of Physics, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0435, USA.

†Corresponding author. Electronic address: boyer@dave.nrl.navy.mil

 
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