convergence with respect to a and c for an hexagonal struc?

Total energy, geometry optimization, DFT+U, spin....

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omar11
Posts: 5
Joined: Thu Oct 20, 2011 6:14 pm

convergence with respect to a and c for an hexagonal struc?

Post by omar11 » Mon Apr 30, 2012 8:48 am

Dear all,

How is it possible to make a convergence study with respect to both a and c for an hexagonal structure?
I have a method but it doesn't look very practical:
To vary "a". And for every value of "a", you vary "c "and the adequate value of "c" is the one for which you get the minimum total energy.

Or is right to to vary only "a" and keep "c" fixed or use the known value of c/a = (8/3)^(1/2)?
I'd appreciate your help!
Omar

ilukacevic
Posts: 271
Joined: Sat Jan 16, 2010 12:05 pm
Location: Dept. of Physics, University J. J. Strossmayer, Osijek, Croatia
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Re: convergence with respect to a and c for an hexagonal str

Post by ilukacevic » Wed May 23, 2012 8:29 am

Dear Omar,

your method is good. But you could also use the automated algorithm for optimization (BFGS) by including the combination of optcell and ionmov variables. This method could be even more useful if you have atoms which need to relax their positions.

Igor L.

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