Dear Prof. Laurence Marks, Hi, Thank you for your inquiry. Calculating the surface dipole of a metal can be an interesting and challenging task. While I cannot provide a personal account of testing the DIPOLE option in AIM, I can suggest an approach that might be helpful.
The surface dipole moment, denoted as $\mu$ in Debye, can be calculated using the Helmholtz equation: $\Delta\Phi = \frac{1}{2\pi\Theta}\frac{\mu}{A}$, where $\Delta\Phi$ is the work-function change in eV, $A$ is the area per ($1\times1$) surface unit cell in $\text{\AA}^2$, $\Theta$ represents the adsorbate coverage in monolayers. The equation expressing the surface dipole moment is given by Eq. (4) of Ref. [Physical Review B, 73, 165424 (2006)], see also Fig. 2 of this reference, where $\mu$ and $\Delta \Phi$ are shown as a function of coverage for O in the fcc-hollow site. The work function, as the difference between the electrostatic potential in the middle of the vacuum and the Fermi energy of the slab, can be calculated using Eq. (1) of Ref. [http://dx.doi.org/10.1016/j.commatsci.2009.09.027], you would also see Fig. 2 of [http://dx.doi.org/10.1063/1.3486216]. I hope this suggestion is helpful to you. Should you have any further questions or require more specific guidance, please feel free to ask. Good luck with your research! Warmest Regards, Saeid Quoting Laurence Marks <laurence.ma...@gmail.com>:
I wonder if anyone has a good suggestion for calculating the surface dipole of a metal (e.g. Al). The DIPOLE option in aim might do it, although I have no idea if that works. If anyone has tested it please let me know; alternatively, if you have an inspiration on how to test it against a calibrant that would be informative. I am always hopeful... -- Professor Laurence Marks (Laurie) Department of Materials Science and Engineering Northwestern University www.numis.northwestern.edu[1] "Research is to see what everybody else has seen, and to think what nobody else has thought", Albert Szent-Györgyi
Links: ------ [1] http://www.numis.northwestern.edu
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