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.