how to calculate stablity of nanotube

[gaurav1201]

hi sir,
 I want to know how to calculate the stability of the nanotube in vnl atk, also how to determine nanotube is metastable, unstable and stable.

[Ulrik G. Vej-Hansen]

Whether a structure is stable or not is really more a question of your thermodynamic reference that which software you are using. However, what i would personally do, would be to calculate the total energy per atom of the CNT in question and compare it to a reference for carbon. Graphene is one option, diamond is another and maybe a third is what is relevant in your case.

[Petr Khomyakov]

To add to Ulrik's post, if you are interested in the thermodynamical stability of your system, then you may want doing molecular dynamics simulations under certain conditions (e.g., constant temperature and so on). The QuantumATK is able to do molecular dynamics at the DFT (quantum mechanically) or classical force field level of approximation.

 I guess you may search the literature to find out the computational framework for this kind of study, and then apply it for the actual system of your interest, using the QuantumATK package. It means that you first have to figure out the methodology of how to approach the problem, and then use the QuantumATK as a computational tool, see many examples of MD simulations at  https://docs.quantumwise.com/tutorials/molecular_dynamics.html, which should give you an idea on technical details of how to run the MD simulations in QuantumATK.