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The Augmented Plane Wave (APW) method, and by extension Linearly-Augmented Plane Wave method are both generalizations of the Muffin Tin Approximation. In both the APW and LAPW methods, the potential $V(r)$ is defined as a piecewise function [1] with a single parameter: the muffin-tin radius $r_\mathrm{MT}$. $$ V(r) = % \begin{cases} \sum_{lm} V_{lm} (r) Y_{...


5

Partial answer, somewhat link-only... The website of Prof. Michel A. Van Hove, Emeritus Chair Professor in Physics and Ex-Director, Institute of Computational and Theoretical Studies, Hong Kong Baptist University is http://www.icts.hkbu.edu.hk/vanhove/#Download_software There you can see links to many LEED simulation packages. See also publications Professor ...


4

There are a few possibilities (the relevant importance of each probably varies depending on the type of scattering and the material). Even for pure C12, neutrons can scatter off unpaired electrons, since many allotropes have unpaired valence electrons. Neutrons can also scatter off the nucleus itself by nuclear forces. Graphite is used in some nuclear ...


4

I have done computational fitting of LEED-IV in the past using an older code and, yes, you are correct. You can do these optimizations on a workstation now for small systems, although I don't recommend it. I ended up doing most of the calculations on a high-performance computer anyway (and you will do that as well for such a large system). For the system ...


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