Structures and absorption spectra of sulfur cluster S9 via first-principles calculations

We have applied a finite-difference pseudopotential density-functional theory in real space with Langevin molecular dynamics annealing technique to determine the ground state structure of S9 cluster, and a linear response method within the adiabatic time-dependent density-functional theory (TDDFT) with the local density approximation (TDLDA) to calculate the optical absorption spectra. It is found that the ground state structure of sulfur cluster S9 belongs to C2 symmetry structure. It seems that our ground state structures of S9 are more stable than other theoretical results. Our results show that the calculated ground state structures of S9 cluster are hardly dependent on the initial structure of S9 cluster. The calculated spectra exhibit a variety of features that can be used for comparison against future experimental investigations.