Note that there can also be a strong difference between odd and even meshes, since you only include the Gamma point in odd meshes. The product, k*a, between the number of k-points, k, in any direction, and the length of the basis vector in this direction, a, should be
A rule of thumb is given by experts from the Technical University of Denmark (DTU): But note very carefully that k-point sampling is use for at least 2 separate things in ATK:ġ) In the selfconsistent loop, the electron density in Fourier space is expanded - these are the "usual" k-points that appear in any DFT code etc. There is no general rule about how many k-points to use, it usually has to be found out from a convergence analysis. Quantities like the electron densities are integrals over k,Īnd the selection of an appropriate k-point grid ensures that these Brillouin zone integrals are converged. The k-points arise from Bloch's theorem, which say that for a periodic solid, the wave function is given by psi_k = u_k e^(ikr).
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