[CP2K-user] Annealing for obtaining the structure of material by AIMD simulation?

Marcella Iannuzzi marci... at gmail.com
Wed Mar 10 07:37:18 UTC 2021

Dear ?

In your input there are so many problems that it is difficult to know where 
to start advising. 
But in the first place, are you really convinced that you want to obtain 
the structure of  (ZrO2)92(Y2O3)8 from the melt with AIMD and a simulation 
cell of ~20 Å per side?
I would consider this a hopeless project. In general nucleating a structure 
from a melt is a so complex problem that there is a whole research branch 
on this and for sure straightforward MD is not the solution, not even using 
much larger boxes and classical force fields. 

Anyway, have you used DFT to check the electronic properties of the melt 
and compared to any known property?
Or do you have any experience with DFT?
Have you tested the DFT settings, like functional, basis set, pseudo 
potential, vdw corrections.
A PW cutoff of 400 eV is extremely small and it is not going to give any 
reasonable result. 
Also LDA is in general not sufficient to obtain reasonable results. 

Looking at your MD settings, you would like to run a constant 
pressure/constant temperature simulation, setting a thermostat, but with 
annealing. It is not clear how a thermostat should behave trying to keep a 
constant temperature while an annealing factor is applied. 
Do you have any experience with molecular dynamics simulations?
Moreover the annealing factor is 0.75, which means that the temperature 
initially set at 1200 K will be decreased to less than 300 K in 5 MD steps, 
which translates in about 3 fs. 
Do you think that this is realistic?


On Wednesday, March 10, 2021 at 6:06:51 AM UTC+1 ji... at gmail.com wrote:

> Dear all,
> I want to obtain the structure of (ZrO2)92(Y2O3)8 by annealing from 1200 
> K(the melting state) and the AIMD simulations,
> but I don't know how to set the input file.
> I build an input file (in attachment)by referring to the cp2k/test 
> examples, but the AIMD simulation can not be done.
> Could you give me some advice?
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