Quantum_espresso_CPMD (or by LAMMPS)

LAMMPS LAMMPS Beginners
1

I am new to MD simulation…now trying to find Diffusivity initially by vacancy induced mechanism in solid electrolyte:
I am seeking verification on the appropriate methodology for calculating diffusion in solid electrolytes using the vacancy mechanism. I have employed two approaches:

Approach A:

1.⁠ ⁠Created a 2x2x2 primitive structure.
2.⁠ ⁠Relaxed the structure using VC relaxation.
3.⁠ ⁠Introduced a vacancy by removing a Li atom.
4.⁠ ⁠Performed electron relaxation.
5.⁠ ⁠Conducted AIMD simulations using CPMD in Quantum ESPRESSO.

Approach B:

Same as Approach A, but with an additional VC relaxation step after introducing the vacancy. and in this case after optimisation , I got reduced volume and its looking somewhat different than the earlier structure.

Both approaches yield different diffusion values. Could you please advise on which approach is more appropriate?

Thank you for your time and expertise.

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Three comments on this:

  • research choices should be based on scientific reasoning and not on public opinion. What if somebody here says choose “A” or choose “B”. Without careful investigation and proper evaluation, it is not possible to provide a meaningful response, so those opinions are just as good as a random number. You would have to have a proper reference to support your choice. “Some dudes on the internet said so”, is not going to give you credit, on the contrary.
  • if you are new to MD, you need to get yourself a proper tutor that can train and advise you. This is not something that you can quickly pick up by yourself since it is as much a craft as a science. And for that you are working agaist 60 years of collected scientific knowledge and many subtle and non-obvious issues that have been found and addressed over those many years
  • Your description is lacking sufficient detail and context to make any meaningful assessment about the validity of your calculations. While you know what your research is about and how you set up your calculations, we don’t and outside of the mention of a Li atom being present, there is no information about what exactly you are simulating. On this abstract level nearly any sequence of steps may be valid or not.
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