Adsorption energy

[khariyahA]

Hi Sir,

I am currently studying about GNR gas sensor and i wanted to find the adsorption energy. I need advice and want to clarify the procedure.

Procedure:
1. i build my structure --> run calculator and optimize geometry.
2. i repeat the structure along c direction and attach the gas at one of the atom (let say H2 gas at carbon).
3. send to calculator, add bandstructure, dos and total energy. I use LDA, FHI for pseudopotential and doublezetapolarized for basis set.

Is the procedure above correct Sir ? and Sir, is it acceptable for the value of total energy if it is too big ?

[mlee]

In the LCAO calculator, the adsorption energy shows better accuracy with Counterpoise correction. When you open the calculator, you can see the Counterpoise section and add it in the script as ticking and selecting the adsorbent. 

[khariyahA]

Thankyou Sir for the reply. I will try it 

[khariyahA]

Hi Sir,

I have include the counterpoise section and select the H2 gas adsorbent. Below is the attachment result of total energy i have obtained. Before that, i want to clarify, the adsorption energy is the total energy, right Sir ?  The total energy i get is still way too big, is it acceptable Sir ? Im confused. From the papers i have read, the adsorption energy is low.

Sir, i would greatly appreciate if you can give me some advice regarding this. Thankyou

[dprai]

Which ATK version are you using?

[khariyahA]

Hi dprai,

Im using latest version, S-2021.06.

[dprai]

There is a formula for adsorption energy calculation. The one you obtained is the CP corrected total energy of the complex.
For adsorption energy do,  total energy of the complex - (total energy of the host + total energy of the gas)

[khariyahA]

Thankyou dprai for the reply 

Is that mean i need to do manual calculation using the formula ? Im still not clear, do i need to do another separate simulation to get ( the total energy of host + total energy of the the gas ) ?

[dprai]

Yes. You have to calculate the total energy of the host material and total energy of the molecules separately. Please check your inbox. I have asked you some query.

[dprai]

You can follow this tutorial.
https://docs.quantumatk.com/tutorials/geometry_optimization/geometry_optimization.html