Modeling the Structural and Vibrational Properties of SiP Diamondoids Nanocrystals via DFT

The spectrum analysis of the Raman and Infrared used alongside density functional theory (DFT) accounts that use Perdew, Burke, Eralzerhof (PBE) functions with a 6-31G basis set. This combination allowed the analysis of vibrational and structural properties. The vibrational frequencies of SiP diamondoids examined, showing a trend of decreasing bond lengths as the number of atoms within the diamondoids increased. This indicates changes in the molecular structure as the size of the diamondoids varies. Various structural properties compared, including bond lengths, tetrahedral angles, dihedral angles, and the energy gap. It observed that the energy gap decreases with an increase in the total number of Si atoms and phosphorus (P) atoms. Additionally, the study found that larger nanocrystals exhibit a decrease in cohesion energy, indicating potential changes in the stability of the crystal structure with size. The study noted that tetrahedral angles and dihedral angles approached the ideal value of 109.43° as the size of the diamondoids increased. This indicates tension towards a more regular and similar molecular arrangement with the growth of the size of the crystal.