Hi, everyone
I'm a beginner to do Ab initio molecular dynamics simulation (AIMD) for NVT ensemble. The software is VASP and my aim is to measure ionic conductivity, activation energy barrier…. ..
According to my understanding, steps in AIMD simulation method could be summarized briefly as follow.
1) At the start of the MD simulations, the it should be assigned an initial temperature according to a Boltzmann distribution.
2) The sample will have heated up to the desired temperature (for e.g. 600K to 1500K).
3) Then it should be equilibrated at the equilibrium temperature for fixed time (e.g. for 5 ps)
4) The MD simulation for diffusion should be then performed for fixed time (e.g. for 40 ps).
But something which is not clear for me is:
- Which INCAR tag is used to fix the equilibrating time at the equilibrium temperature (step 3)
- Which INCAR tag is used to fix the diffusion time (step 4)
Thank you in advance for your cooperation
Hello Yosef,
I'm fairly new to AIMD myself but maybe my thoughts can help you.
I think the easiest way is to develop a kind of INCAR workflow where each INCAR includes the required temperatures and thermostats you want to use. Your simulation time is a result of your time step you choose with POTIM and the number of ionic steps defined by NSW, so:
simulation time = POTIM * NSW [fs]
So you could use one INCAR with TEBEG = 600 and TEEND = 1500, where your chosen simulation time defines your heating rate. Afterwards you do a restart run with another INCAR including POTIM and NSW so that POTIM*NSW=5000 according to your desired simulation time of 5 ps. The same applies to your diffusion run.
In case anybody can see major mistakes in my proposal, do not hesitate to correct me as I am a beginner myself. I hope I could help you!
Best regards
Tim
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