Ab initio study of NMR spectra of Li2S–SiS2 glass system

We obtained the chemical shielding constants of ²⁹Si in Li₂S–SiS₂ glass system on the basis of molecular orbital calculations. The relative chemical shieldings calculated at the HF/6-31G* level is ?16.1 and ?23.8 ppm for E(1) and E(0), respectively. These calculations are in good agreement with the previous NMR study: σ(E(2))>σ(E(1))>σ(E(0)). It is found theoretically that incorporation of Li₂S into SiS₂ does not influence the ²⁹Si chemical shift, while incorporation of Li₂O into SiO₂ does to a significant extent. It is also found that the existence of oxygen in Li₂S–SiS₂ glasses increases the chemical shielding of ²⁹Si by about 25 ppm, which is in good agreement with the experimental result.