Computational Study of Octasilacubane Structural Properties with Density Functional Theory Method

In the present study, the density functional theory method with various basis sets for optimizing and computing the structural and energetic properties of octasilacubane were performed at 298.15 K and 1 atmosphere. The data from the calculations on this compound show us the internal angles in the structure are 90 degrees. For this reason, the molecule has serious angular pressure. This angular strain is tolerated by a higher percentage of p-orbitals of silicon atoms in the Si-Si σ -bonds formation. According to calculation, σ (Si−Si) bonds in the octasilacubane system are formed from an sp 3.44 d 0.02 hybrid. Also, IR and NMR spectra of the structure were simulated. The electronic chemical potential, the hardness and electrophilicity power of the molecule were obtained from frontier orbitals energies. The data show the structure has low electrophilicity. Heats of formation and detonation parameters were then calculated at studied levels of B3LYP (Becke, 3 parameter, Lee-Yang-Parr) theory. The simulation results revealed that this compound because for its high molecular weight is not a viable candidate of high energy density materials (HEDMs).