On Wed, July 8, 2009 11:03, ali kazempour wrote: > Can I use vc-relax to optimize the value of lattice constant in ZnO > wurtzite structure?
Dear ali, of course you can! > Because the lattice constant change and also atomic > positions either. You can nail the atoms to their position by adding " 0 0 0" after the atomic coordinates (see manual for detail), although it only make sense for crystal and possibly alat coordinates, when you are doing vc-relax. > After finishing the run, Which atomic position shoud be > used in next calculation(relaxed position or initial positions)? The optimized ones, if not, why would you do the optimization? > How can I > optimize the value of u that is ideally equal to 3/8? Doing vc-relax, I don't see the problem )I asume you are using this notation: http://cst-www.nrl.navy.mil/lattice/struk/b4.html). If you want the Zn atoms to stay in z=0 you can fix their position as explained above; nevertheless "u" is just the difference in the z coordinate of Zn and O atoms. > thanks a lot you are welcome, best regards -- Lorenzo Paulatto SISSA & DEMOCRITOS (Trieste) phone: +39 040 3787 511 skype: paulatz www: http://people.sissa.it/~paulatto/ ---------------------------------------------------------------- SISSA Webmail https://webmail.sissa.it/ Powered by SquirrelMail http://www.squirrelmail.org/
