Hi Chengyang, You can run a series of calculations with different k-point meshes. The right k-point mesh density can be determined once the total energies converge.
Cheers, Yun On Thu, Apr 25, 2013 at 5:18 AM, Chengyang Li <li.chengyang at wmich.edu>wrote: > Dear all > > I have a question about the K points. When I try to repeat the unit > cell to get a supercell. I found someone said if the structure is changed, > the K points should be changed at the same time if we want to keep the same > result. I try to calculate the phonon of the chromium, the atomic positions > and cell parameters are like this: > > Unit cell > > ATOMIC_POSITIONS crystal > Cr1 0.000000000 0.000000000 0.000000000 > > > CELL_PARAMETERS cubic > 0.500000000 0.500000000 0.500000000 > -0.500000000 0.500000000 0.500000000 > -0.500000000 -0.500000000 0.500000000 > > Supercell, there are two unit cells in this cell. > > ATOMIC_POSITIONS crystal > Cr1 0.000000000 0.000000000 0.000000000 > Cr1 0.000000000 0.000000000 0.500000000 > Cr1 0.500000000 0.500000000 0.250000000 > Cr1 0.500000000 0.500000000 0.750000000 > > CELL_PARAMETERS > 1.000000000 0.000000000 0.000000000 > 0.000000000 1.000000000 0.000000000 > 0.000000000 0.000000000 2.000000000 > > If I set the unit cell like this > > K_POINTS automatic > 4 4 4 1 1 1 > > How should I change the k points in the supercell? > > > Thank you for the attention. > > Chengyang Li > > Western Michigan University, > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum > -- Dr. Yun Wang Research Fellow Centre for Clean Environment and Energy Griffith School of Environment Gold Coast Campus, Griffith University QLD 4222, Australia Tel:(61-7) 5552 8456 Fax:(61-7) 5552 8067 -------------- next part -------------- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20130425/178cc98b/attachment.html
