Structure, transport and surface properties of dense fluids, especially liquid metals
Titel:
Structure, transport and surface properties of dense fluids, especially liquid metals
Auteur:
MARCH, N.H. ALONSO, J.A.
Verschenen in:
Molecular physics
Paginering:
Jaargang 95 (1998) nr. 2 pagina's 353-361
Jaar:
1998-10-10
Inhoud:
The initial focus is on the relation between dynamic and static structure in liquid metals such as Rb near freezing. A Feynman-like model of collective modes and some possible generalizations are summarized, and the simple Feynman model is used to evaluate the fourth moment of the dynamic structure factor S(k, w) in terms of the static structure factor S(k) in the long wavelength limit as k tends to zero. Indeed the central role played by S(0), which is in turn proportional to the isothermal compressibility, is a unifying theme throughout the present study. It is then stressed that when a Debye-like assumption is added, the Green—Kubo formula for the longitudinal viscosity can be employed to estimate this transport coefficient for simple sp metals like Rb near freezing. Utilizing a formula for the shear viscosity at melting that goes back to Andrade, new estimates are presented of the bulk viscosity of some sp metals. Via the long wavelength limit S(0) of the static structure factor, the ratio of shear to longitudinal viscosity at the melting temperature Tm is written as proportional to ρkBTmL/σ where σ is the surface tension, L is the surface thickness, of the order of a molecular diameter, and ρ is the atomic number density. This link between viscosities and surface properties seems to be a new result, and its relation to earlier studies is discussed. An important feature introduced here is the surface thickness L.
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