[QE-users] can i use this trick to do faster MD calculation using pw.x ?

[Jayraj Anadani]

Hello, QE community!
On my metallic system, which has 128 atoms, I am running AIMD calculations
using the pw.x code. Two pseudopotentials, PAW and USPP, were each
tested individually.
I have the following queries:

   1. For a faster AIMD calculation at a specific temperature, *Can I
   perform the whole simulation with a very low "ecutwfc" and "conv_thr" (i.e.
   ecutwfc=5 or 10) below a minimum cutoff of pseudopotential? *So that I
   can get the next ionic position very quickly with a fast scf cycle, then at
   the last MD step I will perform a single point energy (SCF) calculation
   with high "ecutwfc" and "conv_thr" to maintain a good amount of accuracy.
   2. Compared to PAW pseudopotential, USPP's convergence occurs *much more
   quickly. why*? (when ecutwfc is 25)
   3. The temperature fluctuation is incredibly small and nearly equal in
   the MD simulation of thousands of atoms in LAMMPS at a specific temperature
   (i.e., 1000K). However, the temperature fluctuation in MD with pw.x (AIMD)
   is significant, so we must set "tolp" which stands for tolerance for
   velocity rescaling. Although the average temperature is kept constant, *how
   closely does this significant fluctuation match the LAMMPS MD simulation?*

Thank you

regards
JAYRAJ ANADANI
Department of Physics
SPU Research scholar
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20231018/d3968ce7/attachment.html>