[Pw_forum] hello i what vacuum in the relax code for quantum dots calculation .should in the free space applay vacuum or not

[Giovanni Cantele]

A good message is made by: a meaningful subject, a body, name and affiliation.

This being said, if I can understand the subject of your message, it is possibile to study a quantum dot with Quantum-Espresso. Vacuum Space is needed to avoid periodic replica from interacting with each other. Let's suppose, just to make an example, you have a nearly spherical quantum dot, with radius R, you can setup a cubic unit cell with size a=R+V, where V is the vacuum space size. For quantum dots you can use gamma only k-point sampling, because if your calculation is properly done,  no dispersion should show up (flat bands, corresponding to a confined system). Convergence with respect to V must be checked. 

I suggest to read relevant literature, to browse QE web site and tutorials, where lot of information that might be of interest for you is found.

Giovanni

Inviato da iPad

> Il giorno 20 feb 2017, alle ore 21:19, ali mehdizadeh <ali.mehdizadeh.physics1992 at gmail.com> ha scritto:
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