I see two hypothesis: 1 - Some egg box effect.
How big is your mesh cut-off? 2 - In your optimization, you got stuck in some local minima, but when changed the lattice, went to another valley in the potential surface. Moreover, a simple geometry optimization never ensure that you have reached the global minimal energy. On Mon, Oct 4, 2010 at 12:03 PM, Elisa <[email protected]> wrote: > Dear Siesta users, > > I have optimized a solid made by Aluminum nanoclusters. First I relaxed the > atomic coordinates (MD.VaribleCell . false) and, after that, I relaxed the > lattice together with the atomic coordinates. Then I obtained an optimized > solid. > > The problem is that I did some single point calculations changing the > lattice > constant in order to obtain the Energy vs Volume graphic. However, I > realized > that some other structures with different lattice constants are lower in > energy than my optimized solid. > > Do someone know what can be the reason? What I'm doing wrong? > > I appreciate any comment in advance !! > > Thanks, > > Elisa Jimenez Izal > > > Kimika Fakultatea > Euskal Herriko Unibertsitatea - University of The Basque Country > P.K. 1072, 20080 Donostia > Euskal Herria > E-mail: [email protected] > Phone: +34-943-015341 > *********************************************************************** >
