Kun Yin wrote: > Thanks for your reply, Mohnish. > The 'relax' calculation will keep the volume constant but it will fix the > cell parameters, too. For example, if I optimize a tetragonal cell, I want > the c and a axis to change but the volume unchanged. I know this could be > done by varing c/a ratio manually with a series of relax calculation. My > question is, can this be done automatically in QE > Why don't you build a supercell that stores the considering structure. When you do optimization, the volume of supercell will be fixed , but the structure is still optimized.
Hope this help. Linh > ------------------ > Kun Yin > 2010-05-30 > > Dear Yin 'vc-relax' calculation optimizes the structures by the lattice > parameters also but if you set the calculation 'relax' then it optimizes the > geometry within the given fixed volume constraints. This calculation moves > the atom keeping the volume constant within the given symmetry constraint. > hope this helps :) > > On Sun, May 30, 2010 at 6:12 PM, Kun Yin <kyin.cn at gmail.com> wrote: > > >> Dear All, >> >> Does anyone have the experience to do volume fixed optimization with QE, >> which means the structure is optimized allowing all cell parameters and >> atomic positions to vary while keeping the volume fixed? >> >> Kun Yin >> Najing University, China >> 2010-05-30 >> >> _______________________________________________ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://www.democritos.it/mailman/listinfo/pw_forum >> >> > > > > -- ----------------------------------------------------- Nguyen Ngoc Linh, PhD Student c/o: SISSA & CNR-INFM Democritos, via Beirut 2-4, 34014 Trieste (Italy) email: nnlinh at sissa.it phone: +39 04 03787 319 skype: ngoclinh84phys ----------------------------------------------------- "The physics is theoretical but the fun is real"
