ngkpt for geometry optimization

Total energy, DFT+U, BigDFT,...

Moderator: amadon

ngkpt for geometry optimization

Postby mdsimulationgroup » Mon Feb 25, 2019 3:32 pm


I'm very new to planewave calculations; all of my experience is gaussian basis sets. I'm trying to get a feel for the kpoint grid. If all I want to do is geometry optimization of a slab of copper with a molecule absorbed to the surface, how should I be setting my ngkpt? Is it out to have a sparse grid such as:

ngkpt 1 1 1

Or should I have more points?

Posts: 13
Joined: Mon Feb 25, 2019 3:20 pm

Re: ngkpt for geometry optimization

Postby ebousquet » Tue Feb 26, 2019 4:52 pm

Dear Stacey,
When doing a slab, you have one direction that is very large with vacuum (probably the z direction), meaning that your reciprocal space is very small and then the number of k-point can be set to 1 in this direction to have good precision. In the other directions, you need to test the convergence of the k-point grid, i.e. check how your result change w.r.t. number of k-point along x and y (it will depend if you are metallic or not and what is the size of the cell in these directions).
Best wishes,
Posts: 305
Joined: Tue Apr 19, 2011 11:13 am
Location: University of Liege, Belgium

Return to Ground state

Who is online

Users browsing this forum: No registered users and 3 guests