QuantumATK Forum
QuantumATK => General Questions and Answers => Topic started by: narin on August 15, 2022, 19:36

Dear Sirs,
How does QuantumATK calculate the kinetic energy? I looked the help page and the manual but couldn't find any formula.
Thanks.

Calculate total energy & look for log file. There will be all energy contributions.

and to extract from an MD, you can use the Kinetic Energy Distribution from the MD analyzer:
https://docs.quantumatk.com/manual/Types/KineticEnergyDistribution/KineticEnergyDistribution.html

For DFT the kinetic energy is calculated as in any other DFT code (see e.g. https://en.wikipedia.org/wiki/Density_functional_theory and https://en.wikipedia.org/wiki/Kohn%E2%80%93Sham_equations):
T = ⟨T⟩ = ∑_{n} f_{n} ⟨ψ_{n} ħ^{2}/(2m)∇^{2} ψ_{n}⟩
where f_{n} is the occupation number of the n'th state and ψ_{n}⟩ are the KohnSham states.

Thanks a lot for your replies.