Liquid metals radial distribution function

The conduction electrons are scattered by the alkali atoms, the coherence implicit in the radial distribution function. Unlike the case of the scattering of a single electron in a plane wave state by a liquid, discussed previously, in this case the structure factor S(k) must be known up to the Fermi energy (which is 0.5 e.v. — 1 e.v. in saturated metal ammonia solutions). 

Germanium(iv) bromide has been reinvestigated by electron diffraction. Constraining the molecule symmetry to afforded a value of 2.272(1) The electronic radial distribution functions for germanium(iv) and tin(iv) chlorides in the liquid state at 23 °C have been calculated from X-ray diffraction intensity distributions obtained by use of theta-theta reflection diffractometry. Both liquids show intermolecular effects at distances equivalent to the Cl—Cl intermolecular distance. Values of 0.9 D (Si—Cl), 1.5 D (Ge—Cl), and 2.7 D (Sn—Cl) have been derived for the bond dipole moments of these bonds in the metal(iv)... 

The strength of the water-metal interaction together with the surface corrugation gives rise to much more drastic changes in water structure than the ones observed in computer simulations of water near smooth nonmetallic surfaces. Structure in the liquid state is usually characterized by pair correlation functions (PCFs). Because of the homogeneity and isotropy of the bulk liquid phase, they become simple radial distribution functions (RDFs), which do only depend on the distance between two atoms. Near an interface, the PCF depends not only on the interatomic distance but also on the position of, say the first, atom relative to the interface and the direction of the interatomic distance vector. Hence, considerable changes in the atom-atom PCFs can be expected close to the surface. 

Baston et al. [60] studied the samples of ionic liquid after the anodization of uranium metal in [EMIMjCl using the U Lm-edge EXAFS to establish both the oxidation state and the speciation of uranium in the ionic liquid. This was part of an ongoing study to replace high-temperature melts, such as LiQ KQ [61], with ionic liquids. Although it was expected that, when anodized, the uranium would be in the +3 oxidation state, electrochemistry showed that the uranium is actually in a mixture of oxidation states. The EXAFS of the solution showed an edge jump at 17166.6 eV, indicating a mixture of uranium(IV) and uranium(VI). The EXAFS data and pseudo-radial distribution functions for the anodized uranium in [EMIMjCl are shown in Eig. 4.1-12. 

Reliable data are now available for a wide variety of metalUc liquids. Figures 7.1 and 7.2 illustrate the interference function for liquid Pb (a typical quadrivalent liquid metal) at four temperatures. The corresponding radial distribution functions are shown in Figures 7.3 and 7.4 and it should be noted that a(q) depends on temperature and at high q oscillates about the asymptotic value of unity. 

The structure of chlc2 in liquid methanol, specifically the coordination of the chromophore metallic center to the methanol molecules can be discussed by representing the radial distribution function [RDF(r)] related to Mg-O interactions. A relevant issue concerns the coordination number of the metalic center. BOMD results for the structure indicate that the coordination number for Mg of chlc2 in liquid methanol is five [114] a feature that seems to be related with the displacement of the metallic center from the macrocycle plane. This is in contrast with the results from force field calculations that indicate a coordination number of six (four nitrogen atoms plus two oxygen atoms). Several works discussed the coordination of the central Mg atom of porph3rins and chlorophylls in different solvents and environments [112, 118, 134—138]. 

Much more detailed information about the microscopic structure of water at interfaces is provided by the pair correlation function which gives the joint probability of finding an atom of type/r at a position ri, and an atom of type v at a position T2, relative to the probability one would expect from a uniform (ideal gas) distribution. In a bulk homogeneous liquid, gfn, is a function of the radial distance ri2 = Iri - T2I only, but at the interface one must also specify the location zi, zj of the two atoms relative to the surface. We expect the water pair correlation function to give us information about the water structure near the metal, as influenced both by the interaction potential and the surface corrugation, and to reduce to the bulk correlation Inunction when both zi and Z2 are far enough from the surface. 

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