Re: [Wien] Bulk vs supercell Plasma frequency

2015-11-01 Thread Muhammad Sajjad
Dear Professor Blah Thank you for your quick response. Yes I found that completely converged (with the best k-mesh) leads to the same results on changing k-meshes for optical properties. Na is better in k-mesh selection than that of Al. Actually I am expanding structure in z-direction. In my

Re: [Wien] Bulk vs supercell Plasma frequency

2015-10-30 Thread Peter Blaha
Usually, different properties require different k-meshes. So it should be ok to converge the scf with a smaller k-mesh (it still must be a "good" one), but use more k-points for a plot of the DOS or optics. Please repeat the optics calculation with a series of k-meshes and plot w_p as

Re: [Wien] Bulk vs supercell Plasma frequency

2015-10-29 Thread Peter Blaha
In principle you are doing thinks now correct. In reality, however, we use the tetrahedra-method in the integration of the BZ to calculate a joint-density-of-states. And for a metal !!! here there is a difference between k-meshes in the small or large cell. (it is related to the "back-folding"

Re: [Wien] Bulk vs supercell Plasma frequency

2015-10-29 Thread Muhammad Sajjad
Dear Prof. P Blaha Thank you very much for yous fruitful suggestions. However, I did not change RKmax. For cubic Na only W_p_xx is enough but after making supercell (1 1 6) still I need only w_p_xx and forget about w_p_zz, though the system is tetragonal now. Is it right I understood? Second