DigitalCommons@University of Nebraska - Lincoln - Kyungwha Park, M. R. Pederson, L. L. Boyer, Wai-Ning Mei, Renat F. Sabirianov, Xiao Cheng Zeng, Satya Silendra Bulusu, Seamus Curran, James Dewald, Ellen Day, Shireen Adenwalla, Manuel Diaz, Luis G. Rosa, S. Balaz, and Peter A. Dowben: Electronic structure and vibrational spectra of C<sub>2</sub>B<sub>10</sub>-based clusters and films

Research Papers in Physics and Astronomy

Faculty Publications, Department of Physics and Astronomy

Title

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

Authors

Document Type

Article

Date of this Version

January 2006

Comments

Published in Physical Review B 73, 035109 (2006) (9 pages). URL: http://link.aps.org/abstract/PRB/v73/e035109 doi:10.1103/PhysRevB.73.035109 Copyright 2006 American Physical Society. Used by permission.

Abstract

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 roomtemperature films. Calculated energies for removal of hydrogen pairs from carborane molecules are reported.
PACS numbers: 78.30.-j, 31.15.Ew, 36.40.Qv, 81.05.Hd