QuantumATK Forum

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

Title: How does QuantumATK calculate the kinetic energy?
Post 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.

Title: Re: How does QuantumATK calculate the kinetic energy?
Post by: AsifShah on August 16, 2022, 07:01

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

Title: Re: How does QuantumATK calculate the kinetic energy?
Post by: Umberto Martinez on August 16, 2022, 09:03

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

Title: Re: How does QuantumATK calculate the kinetic energy?
Post by: filipr on August 16, 2022, 12:11

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| -ħ²/(2m)∇² |ψ_n⟩

where f_n is the occupation number of the n'th state and |ψ_n⟩ are the Kohn-Sham states.

Title: Re: How does QuantumATK calculate the kinetic energy?
Post by: narin on August 16, 2022, 18:27

Thanks a lot for your replies.