The manual page about ISMEAR is a bit cursory. It's difficult to understand which method to use and when. Can you help me understand it with examples (like Au, CuO, etc.)?
A very good option to understand this topic is to read the articles from VASP, and articles about partial occupancies:
https://www.vasp.at/index.php/documentation
The information on this page about ISMEAR has been really helpful to me.
http://cms.mpi.univie.ac.at/vasp/guide/node124.html
For example in case of Au I would use ISMEAR=1 for structural optimization. But, if I am calculating DOS or other very accurate total energy calculations (no relaxation in metals) I generally use ISMEAR=-5.
Hello Hitanshu,
The rule of thumb of using smearing method in VASP is simple:
- For optimization, Gaussian smearing is safe for all systems (metal, semiconductor and insulator). You may use MP method for metal but should'n use it for semiconductor or insulator.
- For more accurate electronic structure calculation, tetrahedron method should be employed.
- For DFT-MD, fermi smearing is prefer.
However, some background of math and physics behind smearing methods will help you have a clear picture. You may find useful thing here: https://www.vasp.at/vasp-workshop/slides/k-points.pdf
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