Abstract
This study systematically explores the short- and medium-range order of molten GeO2 through the integration of in situ high-temperature Raman spectroscopy, classical molecular dynamics (CMD) simulations, and quantum chemistry (QC) ab initio calculations. CMD simulations show that Ge atoms remain four-fold coordinated, forming [GeO4] tetrahedra interconnected via bridging oxygens into a highly polymerized three-dimensional network. Ring-size statistics reveal that six-membered rings dominate the medium-range connectivity, while smaller three- and four-membered rings also contribute minor motifs. In situ Raman spectra of molten GeO2 display characteristic bands at 428 and 510 cm−1, which are quantitatively deconvoluted into contributions from different ring sizes. QC ab initio calculations of [GeO4] clusters reproduce these spectral features, confirming that the observed Raman band directly corresponds to specific ring topologies. The proportions of ring sizes obtained from Gaussian deconvolution agree closely with CMD simulations, providing the direct experimental validation of medium-range structural motifs in molten GeO2. This integrated experimental–computational approach establishes a coherent structural picture in which tetrahedral coordination and ring-size distribution govern both vibrational behavior and medium-range order in the melt.