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Modeling the Vibrational Properties of InSb Diamondoids and Nanocrystals Using Density Functional Theory
摘要： Raman and infrared spectra were used to obtain the vibrational properties of an indium antimonide crystal. The density functional theory of the Perdew, Burke and Ernzerhof functions/3-21G and the functions’ basis of polarization were employed. This study investigates how the vibrational frequencies of InSb diamondoids change with size as compared to the experimental bulk. The results showed that the bond lengths in InSb diamondoids decreased as the number of atoms within increased. Many physical properties were studied, including energy gaps, tetrahedral angles, dihedral angles, atomic charges, and bond lengths. The high reduced mass mode (HRMM) and high force constant mode were found to be larger in octamantane than in diamondoids, at 211.09 cm?1 and 190.17 cm?1, respectively.
关键词： PBE/3-21G,InSb diamondoids,DFT,Raman spectra,Infrared spectroscopy
更新于2025-09-10 09:29:36
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Electronic, Structural and Vibrational Properties of GaP Diamondoids and Nanocrystals: A Density Functional Theory Study
摘要： The electronic, structural and vibrational properties of gallium phosphide diamondoids and nanocrystals were investigated using density functional theory at PBE/6-31(d) level, which included polarization functions. The energy gap obeyed the quantum confinement size effect with shape fluctuations. The gap converged towards its bulk limit at 2.26 eV. The Ga-P bond lengths of higher diamondoids were found to be distributed around the bulk experimental value at 2.36 Angstrom. Tetrahedral angles were found around the ideal bulk zincblende value at 109.47, degrees while dihedral angles were distributed around the ideal bulk zincblende values at ±60 and ±180 degree. These findings illustrate that diamondoids are a good representative of bulk structure. An analysis of vibrational modes, in terms of reduced masses, force constants and IR intensity, was then performed. The size-related change of certain vibrational frequencies of GaP diamondoids was compared with the experimental bulk. Radial breathing mode frequency began from 187 cm-1 for the smallest molecule GaPH6 and decreased with fluctuations, heading to 0 cm-1 as its bulk limit. Longitudinal optical mode began from 187 cm-1 for the smallest molecule and increased with fluctuations, heading to 376.9 cm-1 (11.3 THz) as its bulk limit. Hydrogen-related vibrations were relatively constant and can therefore be used to identify GaP diamondoids because of their high IR and Raman intensity peaks.
关键词： DFT,Diamondoids,Nanocrystals
更新于2025-09-09 09:28:46