Transport and equilibrium properties of UF₆gas simultaneously fitted by an effective isotropic potential with temperature-dependent parameters

Abstract

All experimental data of the viscosity (71, the second virial coefficient ( 6 ) and the self-diffusion (pD) (103 experimental points altogether) are approximated in the frame of their experimental ermm by means of an effective isotropic ("4) potential with temperaturedependent p m e t e r s . The UF6 gas at given temperature ( T ) is considered as one vibrationally excited state with a sire avenged over all excitations. The equilibrium distance (r,) increases with temperature according to the vibrational excitation of the molecule. The potential depth w'ell ( E ) decreases with enlargement of the equilibrium distance in order to keep the long range forces unchanged.Pxameters of the ground state-ground state interactions (T = 0 K) are derived by means of a minimiwtion of the sum of the squared deviations between experimental and calculated pmpertres normalized to the expenmental error. Appmxm" formulae for the temperature dependences rhff(T). B ( T ) , q ( T ) and p D ( T ) lo be used for accurate and easy calculations are given. A comparison with available (n-6) potentials is made.defining E and r, is described as finding a cross point of calculated B , q, pD and thermal conductivity as a function of E and r,. Nowadays such a procedure may be considered as too simplified, but it produces a good fit of measured 7 and B for mixtures w6-MoF6 and uF6-w&,, where the parameters of the potentia] are calculated as

A Relativistic Density Functional Study on the Uranium Hexafluoride and Plutonium Hexafluoride Monomer and Dimer Species

“…The results for the monomer species are compared with the experimental and other theoretical estimations, and for the UF 6 dimer some discussion of our results in light of refs and and of the behavior of noble gases is presented.…”

pVT –Second Virial Coefficients B(T ), Viscosity η(T ), and Self-Diffusion ρD(T) of the Gases: BF3, CF4, SiF4, CCl4, SiCl4, SF6, MoF6, WF6, UF6, C(CH3)4, and Si(CH3)4 Determined by Means of an Isotropic Temperature-Dependent Potential

“…12 It was introduced in order to speed up the calculations for heavy molecules ͑UF 6 , 23 WF 6 , 23,24 MoF 6 23,24 ͒ and mixtures of different globular molecules. 31 It permits us to obviate some theoretical difficulties bound to the calculation of the viscosity of the considered globular gas as a mixture of different vibrationally excited states.…”

“…These problems make the use of the VESM model inadequate because of the enormously increasing computational time ͓proportional to 1 2 n s (n s ϩ1) ͔. The ITDP has been discussed in detail elsewhere ͑see, for example, Zarkova et al 21,23,26 ͒. It will be outlined here briefly.…”

“…23 x k (kϭl,m) is the relative population of the excited state k ( ͚ kϭ0 n s x k (T)ϵ1). It is calculated as a function of temperature by means of the vibrational partition function…”

Computational Studies of Uranium Hexafluoride Interacting with Functionalized Organics. I. Screening Intermolecular Potentials between UF6 and Small Organic Functional Groups

“…Beu and co-workers have studied the clusters of (UF 6 ) n and the (UF 6 ) 2 dimer within Ar n clusters for spectroscopy applications . Indeed the UF 6 dimer has continued to be a topic revisited by multiple groups, both experimentally and computationally. − One potential reason depleted UF 6 remains unused is that the gas-phase UF 6 reacts with available water vapor to form uranium oxide solids. As such, the important UF 6 –H 2 O interaction has been studied in some detail. − …”