For metals, the default value (SIGMA = 0.2) is sensible. For relaxations in metals use ISMEAR=1 or ISMEAR=2 and an appropriate SIGMA value. For large cells, use Gaussian smearing (ISMEAR = 0) with a small SIGMA = 0.05. The progression of these tutorials follows the abinit tutorial, which I consider to be better as an introduction to DFT than VASP's website.įor semiconductors and insulators, use the tetrahedron method (ISMEAR -5). I have setup a series of steps to get a system up and running based upon what I consider an optimal setup to do computational simulations based on my personal experience and having on-boarded people to do computational materials simulations. To get setup, one should do the relevant portions of the CompMatSci bootcamp to get yourself up and running.
There might be more advanced stuff later involving software I write, but this will likely be in a different section. I am writing a series of tutorials on VASP, which introduces people to computational simulations in a gentile approach which I thnk should be appropriate for advanced undergraduates of materials science/physics/chemistry and beginning graduate students. It uses a plane-wave basis set which makes it more efficient for materials science. More importantly, the pseudo-potential library is widely used which eliminates the problems of having to create a working pseudo-potential library, and usually has cutting edge improvements, such as hybrid functionals, GW, which I personally have little experience in.
The benefit of using VASP is it's wide use, active development. Most of my experience with DFT comes from the use of VASP, although other DFT packages do exist.