[交流] 【求助】DOS计算中，设置ISMEAR=-5为什么还要用SIGMA？已有4人参与

For further considerations on the choice for the smearing method see sections 7.4,8.6. To summarize, use the following guidelines:

For semiconductors or insulators use the tetrahedron method (ISMEAR=-5), if the cell is too large (or if you use only a single or two k-points) use ISMEAR=0 in combination with a small SIGMA=0.05.
For relaxations in metals always use ISMEAR=1 or ISMEAR=2 and an appropriate SIGMA value (the entropy term should be less than 1 meV per atom). Mind: Avoid to use ISMEAR0 for semiconductors and insulators, since it might cause problems.
For metals a sensible value is usually SIGMA= 0.2 (which is the default).

For the calculations of the DOS and very accurate total energy calculations (no relaxation in metals) use the tetrahedron method (ISMEAR=-5).

Originally posted by Prettyswan at 2010-12-15 20:20:10:
在做DOS计算时，要用到四面体方法，设置ISMEAR=-5，那么此时设置SIGMA还有什么用呢？