Authors : Hayder M. Abduljalil and Mudar Ahmed Abdulsattar
Abstract: Local spin density approximation (density functional theory) is used to establish the electronic structure and spectroscopic properties of Aluminum Phosphide (AlP) nanocrystals having (1.02-1.60) nm in diameter. Surface and core parts of AlP diamondoids are studied. Inspected properties include energy gap, Highest Occupied Molecular Orbital (HOMO), Lowest Unoccupied Molecular Orbital (LUMO), cohesive energy and bond length. These properties are compared to confinement theory results. Shape fluctuations are also pointed in size variation. AlP tetramantane vibrational frequencies (IR and Raman) shows that the active region in IR is similar to but with lower intensity than Raman. Size variation of AlP molecules is so that UV-Vis optical peak changes from 282-329 nm heading towards bulk experimental 496 nm as the size of AlP molecules increases. NMR spectra of AlP diamondoids are analyzed with respect to diamondoids constituting atoms. 1H-NMR shielding of AlP diamondoids shows split values. The Al-H shielding is lower in value with respect to P-H shielding. Population analysis of Natural Bond Orbitals (NBO) shows that AlP diamondoids have differences from ideal sp3 bonding of carbon diamondoids. The ratio of surface to core atoms shows that the highest ratio was equal to 1.42 in diamantane structure. This ratio declines with increasing size of molecules and it is dependent on the shape of diamondoids.
Hayder M. Abduljalil and Mudar Ahmed Abdulsattar, 2018. Structural and Spectroscopic Properties of AlP Diamondoids: A DFT Study. Journal of Engineering and Applied Sciences, 13: 4381-4386.