@Earmen, Can you hop over to this chat room?

@HemanthHaridas sure

The explanation you just gave makes more sense to me than the one given in the video

Yeah so did you follow the explanation that I provided in the comment?

Yes, I just ran your code and tried to understand. I think I understand what you did (that's an elegant use of python I must say)

Thank you.

But then there is a problem!

Why I am getting the lattice constant so different than the actual one!

The densities and other parameters do not match

I saw that

I would suggest you try using different pseudopotential files and rerun the calculation

I mean the error is almost 50%. Does quantum espresso underestimate the lattice constant this much!?

I did. I tried with two different pp

Almost identical result

Can I remind you something? The experimental lattice constant in measured at room temperature i suppose, and these calculations run at 0K

This might be a problem. I am guessing this

I don't think so. I just did a quick google search in some research papers about the temperature dependence of Si lattice constant. The difference is only around 0.01 Angstrom

I will try to do the same vc-relax calculation for other well-known materials. I will see if QE continues to underestimate the lattice constant.

You can try graphene, It is inexpensive and well studied using QE

Okay. I will let you know about the results via this chatroom

Great

Can I know what are you doing? I am a PhD student

Hi

I am undergraduate

I am doing volunteer research at the national institute of material science, Bilkent, Turkey. That's why I am learning QE

@HemanthHaridas hemanthharidas.github.io is this you!?

Yes

So you are a professional scientist! Nice. If you are still looking for post-doc position (as you said in your webpage), these are some of the professor working in computational material science and looking for post-docs. You may want to visit their profile:

Can you please give me their profile details? and I am still looking for a position

Thank you for letting me know about open positions

You can easily find their google scholar page

Thank you! I will certainly look into their profiles

Your welcome

@HemanthHaridas, could you give me some direction about learning quantum espresso and DFT in general? Since you are on this field for many years, I am asking you. This is my 4th year in Physics undergraduate education and I learned the basics of ab initio methods, DFT and related concepts (PP, PW expansions, k-points sampling etc). But I want to get an operational knowledge of a software. I started with QE since it is free.

But I am facing lots of problems such as the youtube tutorials are sometimes misleading/don't work, the only proper GUI BURAI is last updated almost 4-5 years ago, I couldn't find any good book or hands-on tutorial on QE! Do you have any suggestions about the learning path of QE/source material for learning? I am mostly interested in 2D materials and DFT of quantum materials with defects.