Size effects on the electronic and vibrational properties of MgO wurtzoids: A density functional theory study

Abstract

The Gaussian 09 software program is used with ab-initio Density Functional Theory (DFT), according to generalized gradient approximation (GGA) of the B3LYP with 6-311G** basis set are used to calculate the electronic and vibrational properties of MgO wurtziods structured at the molecular scale (molecule, cyclohexane), while at Nano-scale included (wurtzoid, wurtzoid2c and triwurtzoid) capped bundle (3,0) nanotube. The electronic properties included density of state, energy gap, and density of bond length, while vibrational properties included infra-red and Raman spectra, reduced masses, force constant as well as longitudinal optical modes were investigated. The Gauss view 05 programs are used to study the geometrical visualization of MgO at molecules and wurtzoids nanostructure. The values of the energy gap of MgO at wurtzoids nanostructure (wurtzoid, wurtzoid2c and triwurtzoid) are as follow (3.9668, 3.66 and 3.44 eV) respectively, these values agree with theoretical values of MgO bulk (4.2 eV) and compared with the experimental value of MgO wurtzite (7.8 eV). The studied vibrational included Raman and IR spectra, force constant, reduce masses, as a function of frequencies and longitudinal optical modes which was around (692 to 720 cm-1) and agreed with experimental results of longitudinal optical of MgO bulk.