supercells and surfaces
compmatphys
supercells and surfaces
If you follow this course in sync with the live classes (September-December), then this chapter is the first part of your main content for week 10 of the fall term (see list of due dates).
So far, we have been looking at perfect single crystals. At most, we squeezed or deformed them, but even then the regular pattern of atoms kept repeating in the same way up to infinity. However, real crystals as we find them in nature or in the lab, are not always perfect. They contain defects (point defects, line defects, planar defects). Sometimes these defects are innocent, sometimes they contribute in an essential way to the observable properties of the crystal.
How do we model defects by DFT, using codes that have periodic boundary conditions? That’s what this chapter is about. The same strategy — using supercells — can also be used to model surfaces. And also to mimick free atoms.
Going thoroughly through this chapter will take you about 2h30m. (don’t forget the next chapter, which is part of this week’s material too)
Making DFT calculations for bulk crystals is fine, but many properties of real materials arise due to impurities and defects. Or are due to layering. How to deal with that? For periodic DFT codes, the answer is: supercells.
Expected time: 1h30m
Apart from having defects, crystals are not infinite either. They are terminated by surfaces. How to handle that with a DFT code with periodic boundary conditions? And can surface-specific properties be calculated that way?
Expected time: 60m
Are you still on board?
Here you can find the recording of the feedback webinar of this week.