Electronic and vibrational spectroscopic properties of GaAs diamondoids using Density Functional Theory

Abstract

In the present work we study the electronic structure, FTIR and Raman spectra of GaAs diamondoids structure as a function of particle size and shape by using density functional theory at the generalized gradient approximation level of Perdew, Burke and Emzhof (PBE), through Gaussian 09 program with 3-21G basis states.  The frequencies in the vibrational spectrum are analyzed against reduced masses, force constants and intensities of vibration. The results show that both total energy and energy gap decrease in their value as the nanocrystals cluster grow in size. Diamondoids structure molecule used to vary the nanoparticals size being of standard shape and size. Diamondoids have the least surface effects so the trends can point towards bulk properties. Results showed that GaAs bond lengths generally decrease as the number of cages increases with remarkable dependence on the shape of the diamondoids molecules.  Tetrahedral angles and bond lengths are used to compare different sizes of GaAs diamondoids molecules.