# Adsorption calcs using Quantum ESPRESSO

I already built a copper surface using BURAI and I used an SCF calculation to find the total energy of this surface. Now, what is the next step to finding the adsorption energy of one H2 molecule on this surface?

• +1 and welcome to our new community! We hope to see much more of you in the future!!! Thank you for contributing your question here. Oct 31, 2022 at 20:40
• Take a look at the discussion here.
– Camps
Oct 31, 2022 at 20:54

Step 1

Calculate energy of copper slab with hydrogen molecule on slab: $$E(Cu+H_2)$$

Step 2

Calculate energy of copper slab: $$E(Cu)$$

Step 3

Calculate energy of hydrogen molecule: $$E(H_2)$$

$$E^{ad}(H_2)$$ = $$E(Cu+H_2)$$ - $$E(Cu)$$-$$E(H_2)$$

Hydrogen adsoption on copper surface will vary with different binding sites such as hollow/Bridge site and with different crystallography orientation (For example $$E(100)\neq E(110)$$).

• Sir, thank you so much. Let me know if I understood. After I know the total energy for surface copper using the SCF calculation, do I need to make the same procedure for H2 molecule? I mean, do I need to know the total energy for H2 using the SCF calculate Nov 8, 2022 at 22:56
• Yes, you need three calculation 1) copper surface with H2 2) copper surface without H2 and 3) H2 only . You need to perform atomic relaxation, as well as surface atoms, will move. For the hydrogen molecule, create a large box (10 Ang), put the H2 molecule, and calculate minimum energy of that molecule (allow atoms to move). Nov 9, 2022 at 4:44
• Thanks for the advice. Nov 9, 2022 at 12:31
• Sir, where can I find files for H2 molecules For solids, I am using AMCSD and put in BURAI, but where can I find molecules files? Nov 11, 2022 at 3:31
• Use a separate question in forum Nov 11, 2022 at 3:37