What parameter affect the total energy?

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zhuanghl
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What parameter affect the total energy?

#1 Post by zhuanghl » Wed Jan 18, 2006 3:37 pm

What parameter affect the total energy?Except some key parameters,such as Cutoff energy,K-point,FFT grid.Well,I mean that for example,I set different Mixing parameters which all could make the system to converge(Of course,other parameters are kept the same).Should the total energy in this case be the same or not?
Thanks!
Last edited by zhuanghl on Wed Jan 18, 2006 3:37 pm, edited 1 time in total.

konglt

What parameter affect the total energy?

#2 Post by konglt » Wed Jan 18, 2006 4:15 pm

I guess they should be the same.
Last edited by konglt on Wed Jan 18, 2006 4:15 pm, edited 1 time in total.

tjf
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What parameter affect the total energy?

#3 Post by tjf » Wed Jan 18, 2006 4:34 pm

My understanding is that if the parameters are related to the electronic iteration (as opposed to the expression of the density/wavefunction or the determination of an energy from that density/wavefunction), then changing those parameters does not affect the final energy if the electronic energy converges.

Anyone else care to comment on this?
Last edited by tjf on Wed Jan 18, 2006 4:34 pm, edited 1 time in total.

zhuanghl
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What parameter affect the total energy?

#4 Post by zhuanghl » Thu Feb 16, 2006 10:34 am

Could someone else give more detail?Thanks!
Last edited by zhuanghl on Thu Feb 16, 2006 10:34 am, edited 1 time in total.

admin
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What parameter affect the total energy?

#5 Post by admin » Fri Feb 17, 2006 10:22 am

I recommend to read
1) the online-handbook, chapter 9: "The most important parameters, source of errors"
2) the tutorial-file "accuracy.pdf" of the VASP-wokshop, which you can download from http://cms.mpi.univie.ac.at/vasp-workshop
they summarize all parameters which affect the calculated total energies
(choice of POTCAR, k-mesh, BZ-integration, PREC, ENCUT, ENAUG,...)
Mixing should never affect the converged total energies themselves, only the
convergence rate.
Last edited by admin on Fri Feb 17, 2006 10:22 am, edited 1 time in total.

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