QuantumATK Forum
QuantumATK => General Questions and Answers => Topic started by: duygu on June 2, 2009, 13:59
-
Is there any way to utilize the fixed spin tag for periodic calculations?
-
No, it can only be used for molecular calculations.
If you have a particular application for this functionality in mind, it would be interesting if you could share it with us!
-
While optimizing atomic coordinates of a magnetic system, I noticed that magnetic moment per cell changes with lattice constant. For this reason I want to fix moment at first, then make optimization calculations for different lattice constants. Repeating this procedure for different moments, I obtain different magnetic branches of the structure. The branch with minimum energy configuration will be ground state, I assume.
-
Interesting idea. Although, I'm not sure the results will be different compared to if you just allow the magnetization to be free. ATK will adjust the magnetization to its minimum energy configuration for each lattice constant, so in the end you should end up in the same global minimum (provided it's not blocked by very high energy barriers separating local minima, but that's a risk you always face with any kind of optimization).
In the end, the magnetization is just another degree of freedom, so the situation would be quite similar if you try to optimize, say, the a and c lattice constants of a hexagonal structure by keeping a fixed (lattice constant) and scanning c (magnetization), or keeping c fixed and scanning a. Running the self-consistent loop is pretty much the same as scanning the magnetization.
-
I agree with Anders.