Uncommon features in the dynamic structure factor of a molten transition metal

• Published in: Journal of non-crystalline solids 2007-10, Vol.353 (32-40), p.3113-3121
• Main Authors: Bermejo, F.J., Fernández-Perea, R., Cabrillo, C.
• Format: Article
• Language: English
• Subjects: Acoustic properties; Brillouin scattering; Condensed matter: structure, mechanical and thermal properties; Density-functional theory; Diffraction and scattering measurements; Electrical and electronic properties; Exact sciences and technology; Geology; Lattice dynamics; Liquid alloys and liquid metals; Modeling and simulation; Neutron diffraction/scattering; Phonons; Physics; Terahertz properties and measurements; Vibrational states in disordered systems
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2007.05.155

The collective SC(Q,ω), single-particle SS(Q,ω) dynamic structure factors as well as the spectra for transverse-current correlations CT(Q,ω) for molten nickel close to melting have been calculated from a massive molecular dynamics simulation using an Embedded Atom Model potential. A number of features are found in the structure factors that are absent in the spectra of simpler liquids such as molten alkali metals. Estimates for the shear component of the generalized, wavevector-dependent viscosity are obtained from analysis of CT(Q,ω). Such data together with those concerning the strength of the thermal conduction channels for the excitation decay enable us to subtract such contributions to form the linewidths of Brillouin peaks and thus to evaluate the Q-dependent bulk viscosity coefficient. The result shows that contrary to inferences based upon geophysical data, both bulk and shear-viscosity coefficients are of the same order of magnitude.