Is there a means to estimate (dirty estimate) the expected contribution of Cuolombic Interactions in uranium hexafluoride UF6?
Hi Ali--
In gas phase? In liquid phase? Please give us more details.
Your question is very open-ended...
Best,
--Keith
@KeithDPatch
Dear Keith
Thank you for your interest. I am interested in answer for both vapor and liquid phases.
Regards
Ali
Ali, you need to explain what you mean. The Coulombic contribution to what? Under what circumstances? In what context?
UF6 is a perfectly symmetric molecule, so between molecules separated by more than one Å or so, there should be no Coulomb interaction...
Dear Jonas
Thank you for your interest. I am looking into the thermophysical properties of UF6 for Vapor-Liquid Equilibria (VLE). I have optimized the Lennard-Jones potential parameters using temperature dependence. However, the simulation results are not as satisfactory as noble gases. I am assuming that electrostatic contributions play a role in this case?
The potentials for noble gases are well known and most force fields perform very well for them. It is unlikely you can obtain the same accuracy.
With fluorine you have the issue with its anisotropic repulsion, fluorine atoms are not spherical. In a Lennard-Jones, that will not be accounted for and this might affect the density of the liquid phase. For condensed phases, the Buckingham potential is more accurate.
I will calculate atomic partial charges for you, wait a minute.
Thank you Jonas. Appreciate your help. I would appreciate it more if you take a look into this article.
Article Vapor–liquid phase equilibrium diagram for uranium hexafluor...
I'm working on calculating partial charges on U and F in UF6. Currently trying PBE0 with 6-311G* on F and a Stuttgart RLC ECP basis set by W. Kuechle, M. Dolg, H. Stoll, H. Preuss, Mol. Phys. 74, 1245 (1991). A pseudopotential is used for the core electrons of U.
Partial charges is obtained by fitting to reproduce the electrostatic potential outside the molecule. Universial Force Field atomic radii were used for the ESP fit. Calculations were done in Gaussian09.
I got +2.758446 on U and -0.459741 on average for F. There is a Jahn-Teller effect, which I'm assuming you don't consider.
You can try to include these partial charges.
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