Excited States of Silicon Carbide Clusters by Time Dependent Density Functional Theory
Abstract
Previous AFIT research with density functional theory (DFT) has shown DFT to be accurate for the ground states of small SimCn (m,n < 5) clusters. Evaluating the accuracy of time dependent DFT (TDDFT) to calculate the excited states of these clusters was the focus of this research. It is shown that for the excited states that can be expressed as a single electron configuration, energies calculated are generally within .1 e V or better of experimental differences. A possible scheme for correcting multiconfigurational singlet states, is also presented, which also brings their energies to within .1 eV of experiment. Calculations on larger, cage-like structures show excitation energies consistent with spectroscopic measurements of SiC surface defects, suggesting the possibility that the SiC surface forms similar clusters. Calculations on the equilibrium geometries and vibrational frequencies of yet unobserved states of the smaller clusters can aid in their detection in interstellar atmospheres and the laboratory. Finally, this research offers further insight into how silicon and carbon interact with one another as stoichiometry changes, which may one. da lead to better semiconductors for aerospace applications.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 2004
- Accession Number
- ADA426785
Entities
People
- John E. Boyd
Organizations
- Air Force Institute of Technology