Hi Sophia, As per my experience, you can reduce the k-mesh in the direction in which you are increasing the size of your supercell. The k-mesh density, in general, is inversely proportional to the size of the unit cell.
This means that you should be able to get the converged result for a single gamma point calculation too, if you can manage to make your supercell large enough. Before following this suggestion, I would like you to wait to hear from other experienced SIESTA users as I am also relatively new to this. Best Regards, Ravi On Tue, May 19, 2009 at 10:01 AM, Sophia Nishad <sophia.nis...@gmail.com>wrote: > Hi Siesta users, > > I have a question regarding convergence of phonon calculation with respect > to k-mesh. > > Suppose for an 8 atom (1x1x1x8) Si supercell Monkhrast k-mesh required is > 16x16x16 for Gamma point phonons. If I now double the size of the supercell > in one of the axial directions and have 16 atoms (2x1x1x8) how would the > k-mesh be resolved for this larger supercell? > > To get the k-mesh denser like for the case of 8-atom supercell, we would > need to use 8x16x16; but would it be necessary to use such equivalent dense > mesh or due to the increase of the supercell size we can use less denser > k-mesh, say, 8x8x4? > > Thanks in advance, > -- > Sophia >