4
$\begingroup$

Dynamical stability is checked by a phonon curve. Thermal stability is checked by a molecular dynamics simulation. What is the difference between them?

$\endgroup$
2
  • 2
    $\begingroup$ +1 and welcome to MMSE! If by phonon curve you meant phonon dispersion relation, then yes, you can get an idea of that material's dynamical stability. I have no experience in molecular dynamics but afaik, MD simulation is done for finite temperature whereas DFT is for zero temperature. So, a phonon dispersion relation can give you info about how a material behaves against small perturbation (dynamical stability), whereas a MD simulation shows the material stability over time at a finite temperature. Does it help? $\endgroup$ Commented Mar 14 at 10:01
  • $\begingroup$ Thank you. I do not understand when shall we calculate the dynamical stability and when shall we calculate the thermal stability? Why do we need both? Is doing one enough? $\endgroup$ Commented Mar 17 at 0:01

1 Answer 1

3
$\begingroup$

Let's see what is the difference between the two things that you are looking for:

  1. Dynamic Stability: This is usually calculated from ab-inito calculations, where you calculate the dynamic matrix for the molecule at every k-point and then evaluate it's eigen vectors and eigen values to find the phonon dispersion curve. This is usually done at 0K and will tell you if you have reached a minimum on the potential energy surface. I should also note that you can calculate phonon curves from MD simulations (LAMMPS can do this).

  2. Thermal stability: It is not immediately clear if you are asking if MD can give you information about if a material is combustible, or if a material is stable at a temperature greater than 0K. If you are looking for the latter, You can very well perform an MD simulation of the system at any temperature of your choice and see if the structural integrity is conserved. However, if you are looking for the former, you might have some luck with ReaxFF and associated techniques.

$\endgroup$
2
  • $\begingroup$ Thank you. I am doing dft study of a 2D material. I am not asking about combustible. I am asking about stability. Which stability test should I do? I do not understand. In the paper they sometimes do dynamical stability test, sometimes they do thermal stability test, sometimes they do all tests together. $\endgroup$ Commented Mar 17 at 0:05
  • 1
    $\begingroup$ If you are doing DFT studies, you would probably want to do the dynamical stability, where you look into the phonon dispersion. $\endgroup$ Commented Mar 17 at 0:47

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .