Anomalous dispersion of the acoustic mode in liquid Bi
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nelastic x-ray scattering measurements on liquid Bi were carried out. Prominent acoustic mode excitations were observed in the dynamic structure factor to beyond 12nm−1, which resolves previously conflicting results as to their presence beyond 6nm−1. We find the dispersion curve of the excitation energy with momentum transfer is nearly flat from 7 to 15nm−1 consistent with ab initio calculations of liquid Bi [J. Souto et al., Phys. Rev. B 81, 134201 (2010)]. Our ab initio and classical molecular dynamics simulations suggest that a long-range force is needed to reproduce the flatness of the dispersion curve, and the long-range force is correlated with a local structure consisting of shorter and longer bonds in the liquid.
- Physical Review B
Physical Review B 92(5), 054206-1-054206-8, 2015-08-25
American Physical Society