View source for Electronic properties of 2D and 1D systems

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Prev:[[LabQSM#Module 3: Low dimensional structures (6h)]]

==Input set-up for a low dimensional system:==
Now we want to deal with systems of reduced dimensionality, e.g. periodic in one or two dimension but isolated in the other directions. This is accomplished by:

* Isolating the system in the non-periodic dimension as seen in [[Electronic properties of isolated molecules]], so inserting an amount of vacuum in the supercell.
* Sampling the Brillouin zone that now has reduced dimension:

In Quantum ESPRESSO one needs to set the following:
   K_POINTS automatic
   nk nk 1   0 0 0         # for Gamma sampling using complex wavefunctions
                         # deprecated, unless for testing or debugging
this will generate a 2D sampling.
In brief: you will need large supercells because of the present of vacuum which reflects in a large number of plane waves and a converged sampling of the BZ. The combination of this two issues makes the calculations of 2D system rather cumbersome.

==Exercises:==
===Exercise 1:===