Dear Lily, I don't know what was the error in your attempted extracting lines from files; this is not Siesta but Unix stuff; most probably you messed up with >, <, and spaces (or, lines you searched for were not in your files). However, I'd have couple of comments on the meaning of the test you are doing.
1. Not the input MeshCutoff matters, but the actual numbers of division along lattice vectors accepted by the system. Search in the output for e.g.: | InitMesh: MESH = 40 x 40 x 40 = 64000 | InitMesh: Mesh cutoff (required, used) = 350.000 425.493 Ry Therefore, small changes of input MeshCutoff might not change the mesh at all. 2. You can eventually extract total energies, make a plot and look at it, but attention! It is IMPOSSIBLE to decide whether the energy is "converged" or not without specifying the relevant order of magnitude of DIFFERENCES you are interested in to study, like e.g. the effect of atom displacement, changing magnetic configuration, imposing pressure, etc. Best regards Andrei > Dear All, > > When i tried to look into how the meshcutoff affects the total energy, i > used several meshcutoff values, if I take CH4 as an example, 25, 35, 55, > 85, and 125, > > to avoid manually recording energy and meshcutoff, I followed the H2O > example, in which they investigate how cell size influences the energy > > using commands like: > > siesta<h2o.fdf>h2o.5ang.out &tail -f h2o.5ang.out > ... .... > > siesta<h2o.fdf>h2o.35ang.out &tail -f h2o.35ang.out > > grep " Total=" h2o.*ang.out >convergencecellsize.dat > > > then you will obtain your size and energy in each case in > convergencecellsize.dat file. > > When I used > siesta<ch4.fdf> ch4.25mesh.out & tail -f ch4.25mesh.out > ... .... > siesta<ch4.fdf> ch4.125mesh.out &tail -f ch4.125mesh.out > > grep " Total=" ch4.*mesh.out >convergencemesh.dat > > Somehow, convergencemesh.dat is empty in my case, what's wrong? > > Many many thanks for any hint! > > Lily >
