Jean W. Henry

Date of Award


Document Type


Degree Name

Master of Science


Department of Engineering Physics

First Advisor

Larry W. Burggraf, PhD


Density Functional Theory (DFT) method was employed to model silicon carbide small clusters. Comparing the DFT calculation results with experimental results that observed by using photoelectron spectroscopy (PES), DFT predicts the same structures that experiment observed. For electron affinity, DFT results are in good agreement with experimental results, the root mean square negative offset 0.1 eV found using medium size of basis set (cc-pVDZ+) calculation. DFT results for vibrational frequencies are in good agreement with experiment results; the root mean square error is 72.5 cm-1 wave number. 16 ground state structures of SimCn (m ≤ 4, n ≤ 4 ) clusters were found using DFT:B3LYP/cc-pVDZ calculations, the properties of these structures were discussed. The calculation accuracy of electron affinity is affected by the properties of basis sets. Increasing basis set size improves the energy results of singlet and triplet state more than the energy result of doublet state; adding diffuse functions into basis sets dramatically improves the energy result of doublet state. Computational time scaling of DFT computations in SiC system was conducted. A brief an accuracy assessment study of AM1 semi-empirical method for SimCn clusters was also performed.

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DTIC Accession Number