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

Authors

Kyungwha Park, Georgetown UniversityFollow
M. R. Pederson, Naval Research Laboratory, Washington D.C.
L. L. Boyer, Naval Research Laboratory, Washington D.C.Follow
Wai-Ning Mei, University of Nebraska at OmahaFollow
Renat F. Sabirianov, University of Nebraska at OmahaFollow
Xiao Cheng Zeng, University of Nebraska-LincolnFollow
Satya S. Bulusu, University of Nebraska-LincolnFollow
Seamus Curran, New Mexico State UniversityFollow
James Dewald, New Mexico State University
Ellen Day, University of Nebraska-Lincoln
Shireen Adenwalla, University of Nebraska-LincolnFollow
Manuel Diaz, University of Nebraska-Lincoln
Luis G. Rosa, University of Nebraska-LincolnFollow
Snjezana Balaz, University of Nebraska-LincolnFollow
Peter A. Dowben, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

1-9-2006

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