QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: Habib on October 8, 2023, 00:37

Title: Gibbs free Energy Calculations
Post by: Habib on October 8, 2023, 00:37

Hello,

I'm trying to figure out the Gibbs free energy for a reaction on the LaFeO3(100) surface. I read some forum posts and found out that the "IdealGasThermochemistry" object can help with this, but my QuantumATK version (Q-2019.12) doesn't have it. We're planning to upgrade, but it'll take some time.
To calculate Δ𝐺, we need to find Δ𝛦, Δ𝐸𝑍𝑃𝐸, and Δ𝑆. I already have Δ𝛦, which is -0.06 eV, and I can get 𝐸𝑍𝑃𝐸 and S for the isolated molecules from a database. But I'm not sure how to calculate the Zero-Point Energy (ZPE) corrections and the entropy change for the LaFeO3(100)@H system in QuantumATK Q-2019.12.
Is there an easy way to do this or a script that can help me extract ZPE and S from the optimized file of LaFeO3@H? Your guidance would be much appreciated!

Kind Regards
Habib

Title: Re: Gibbs free Energy Calculations
Post by: Habib on October 12, 2023, 13:26

If someone can help?

Title: Re: Gibbs free Energy Calculations
Post by: Anders Blom on October 17, 2023, 00:24

The ZPE can be obtained as a query method on a PhononDensityOfStates (https://docs.quantumatk.com/manual/Types/PhononDensityOfStates/PhononDensityOfStates.html) , but computing the entropy is too complex to provide a simple answer to here, as it includes translational, rotational, vibrational, pressure and electronic contributions.