  This article provides a comprehensive investigation on the chemical bonding,
electronic structure, and spectroscopic properties of the lanarkite-type PSO
structure from a computational perspective. Thus, different functionals in the
field of DFT (e.g., PBE, PBE0, PBESOL, PBESOL0, BLYP, WC1LYP and B3LYP) using a
triple-zeta valence plus polarization basis set were assessed to accurate
prediction their fundamental properties. Among all DFT functionals tested in
this study, in particular, the PBE was the one that showed the best agreement
with the experimental data available in the literature. Our results also reveal
that the [PbO$_5$] clusters are formed with three different Pb--O bond lengths,
with values of about 2.32, 2.59 and 2.84\AA, respectively, and the [SO$_4$]
clusters have the same S--O bond length of 1.57\AA. We then performed a
complete topological analysis of this system to better understand these
structural differences. Additionally, the PSO structure has an indirect band
gap energy of 2.9 eV and an effective mass ratio of about 0.415 (using PBE
calculations) which may, in principle, indicate a low recombination of
electro-hole pairs in the lanarkite structure. Therefore, we believe that a
detailed understanding of their electronic structure and spectroscopic
properties as well as their chemical bonding is critically important for
developing new technologies based on PSO.
