Thak you so much dear Andria, So you suggest that I can use diagon for a system consisted of about 730 atoms? But I recieve error at the very beginnig of the calculation and the job terminates badly! I thought it might be because of that. But if that's ok with diagon, I must go over it again and give it another shot.
Sincerely yours, B. Fakhraei On Tuesday, August 2, 2016, Andrei Postnikov < [email protected]> wrote: > Hi, > I think there must be some misunderstanding: > the Siesta rule of thumb about ~100 atoms implies only that > for large enough system, O(N) might ultimately provide > better scaling than diagon, and ~100 is a rough estimate > of when the crossing of ~N^3 and ~N tendencies happens in practice. > However, O(N) only works with large enough band gap, and is otherwise > fragile. > There is nothing wrong about using diagon to systems of any size, > and 100 atoms are not that many to make it markedly unpractical. > I'd say, go ahead with diagon as long as the calculation time > is not a problem. If it starts to become an issue > and you think you can gain by switching to O(N), > do some test on whether it works correctly and is indeed faster. > > Best regards > > Andrei > > > ----- RCP <[email protected] <javascript:;>> a écrit : > > Hi, > > > > I'm not an expert here, but the naive answer is "use order N > > method". However, that depends on the physics of your system, > > for instance, O(N) cannot be applied to metals. > > > > Regards, > > > > Roberto > > > > > > On 08/01/2016 05:42 PM, Bahareh Fakhraei wrote: > > > Hello every one, > > > > > > For relaxing the large systems (more than 100 atoms) in SIESTA, > seemingly > > > *diagon* is not a good option for solution method. Why and What should > be > > > used instead? > > > > > > yours, > > > > > > B. Fakhraei > > > > > > A beginner to SIESTA program > > -- >
