You right, you should perform 2 structural relaxations. Before doing this do calculations without geom. optim. with different density of kpoints by "%block kgrid_Monkhorst_Pack" and see convergence of kpoint density on forces. This also should be checked for meshcutoff - convergence in forces is very important for geom. optim.
2014-07-21 6:59 GMT+04:00 邵德喜 <dxshao...@gmail.com>: > Thanks very much. > Do you mean that I should do structual relaxation twice?First with > MD.VariableCell > False,then with MD.VariableCell True? > If I could just do structual relaxation once with MD.VariableCell True? > And if " kgrid Monkhorst Pack" option can be reserved at the same time? > Yours Sincerely! > Dexishao > > > 2014-07-21 4:55 GMT+08:00 Максим Арсентьев <ars21031...@gmail.com>: > > Dear, Dexi! >> >> You can vary residual strain by MD.MaxStressTol. >> Use CG, relax with MD.VariableCell False first, then input coordinates >> obtained to a new file with MD.VariableCell True. >> Note you may need to shift some atoms manually before geometry >> optimization: if all atoms are in 2D plane, then all of them will remain in >> plane after geom. optim. because z forces are zero, so you need to shift >> any atom to unlock z forces and avoid such a false state. >> >> >> 2014-07-20 4:01 GMT+04:00 邵德喜 <dxshao...@gmail.com>: >> >> Dear everyone: >>> I really want to know how to get a structure wuthout strain.For example >>> ,Let's consider graphene ,I get the structure from materials studio,and use >>> it as initial one for siesta structual relaxation. >>> If in the relaxation set some options as follows: >>> MD.TypeOfRun CG/Verlet >>> MD.VariableCell True >>> ... >>> At the same time ,I replace " kgrid Monkhorst Pack" option with k-grid >>> cutoff. >>> When the relaxation is done,I want to ask if the final structure after >>> relaxation is >>> one structure without strain? >>> In general ,how to get a structure without strain is what I care. >>> Thanks in advance. >>> Dexi Shao >>> >> >> >> >> -- >> Best wishes, >> Maxim Arsent'ev, D.Sc.(Chemistry) >> Laboratory of research of nanostructures >> Institute of Silicate Chemistry of RAS >> > > -- Best wishes, Maxim Arsent'ev, D.Sc.(Chemistry) Laboratory of research of nanostructures Institute of Silicate Chemistry of RAS
