Welcome to QE Book Discussions!

[nguyen-group]

Dear Readers,

Thank you for using our book and welcome to the discussion.
We’re using Discussions as a place to connect with the readers. We hope that you:

• Ask questions about the contents of the book, such as difficulty in installation, etc.
• Share your impressions about the book.
• Report the error or bug of the input files.

Any suggestions to improve the book are welcome.

On behalf of the authors!

[r-saito-sendai]

Hi. I, Saito is a co-author of the book. Thank you for your interest on our book. Any questions or comments are welcome.

[gabriel-2023]

Hello Nguyen and Saito, I want to learn how to use Quantum Espresso and I am following your book to install it. Unfortunately, I have run into problems while following your installation procedure.

1. when I type jupyter-lab it says No web browser found: Error('could not locate runnable browser').

2. when I type mpirun -np 4 pw.x < scf.in > scf.out & I get the following message
   Note: The following floating-point exceptions are signalling: IEEE_UNDERFLOW_FLAG IEEE_DENORMAL
   Note: The following floating-point exceptions are signalling: IEEE_UNDERFLOW_FLAG IEEE_DENORMAL
   Note: The following floating-point exceptions are signalling: IEEE_UNDERFLOW_FLAG IEEE_DENORMAL
   Note: The following floating-point exceptions are signalling: IEEE_UNDERFLOW_FLAG IEEE_DENORMAL

3. When I type xcrysden & it is displayed like in the following picture
   

Can you help me out to install correctly Quantum Espresso please.
Regards
Gabriel

[nguyen-group]

Hi,

1. when I type jupyter-lab it says No web browser found: Error('could not locate runnable browser').

Can you see something like a ULR? http://localhost:8888/?token=d0a958999d7e59da3f097809882e8f40eb5845e3a07cebe8
you can copy and paste it into your web browser.

2. Note: The following floating-point exceptions are signalling: IEEE_UNDERFLOW_FLAG IEEE_DENORMAL
   This is not an error but a message. I think pw.x program can still run normally.

3. When I type xcrysden & it is displayed like in the following picture
   I never see it, so I have no idea yet. Another choice is to reinstall everything.

By the way, which Linux OS that you install in Windows?
If you want to use the Windows, I suggest the install Ubuntu on WSL2 (https://ubuntu.com/tutorials/install-ubuntu-on-wsl2-on-windows-11-with-gui-support#1-overview)

[gabriel-2023]

Thank you very much for your response. I have reinstalled everything and now it is working fine. Thanks again Regards Gabriel

…

________________________________ De: Quantum Materials @ Tohoku University ***@***.***> Enviado: martes, 12 de diciembre de 2023 15:28 Para: nguyen-group/QE-SSP ***@***.***> Cc: GABRIEL GONZALEZ CONTRERAS ***@***.***>; Comment ***@***.***> Asunto: Re: [nguyen-group/QE-SSP] Welcome to QE Book Discussions! (Discussion #2) Hi, 1. when I type jupyter-lab it says No web browser found: Error('could not locate runnable browser'). Can you see something like a ULR? http://localhost:8888/?token=d0a958999d7e59da3f097809882e8f40eb5845e3a07cebe8 you can copy and paste it into your web browser. 1. Note: The following floating-point exceptions are signalling: IEEE_UNDERFLOW_FLAG IEEE_DENORMAL This is not an error but a message. I think pw.x program can still run normally. 2. When I type xcrysden & it is displayed like in the following picture I never see it, so I have no idea yet. Another choice is to reinstall everything. By the way, which Linux OS that you install in Windows? If you want to use the Windows, I suggest the install Ubuntu on WSL2 (https://ubuntu.com/tutorials/install-ubuntu-on-wsl2-on-windows-11-with-gui-support#1-overview) — Reply to this email directly, view it on GitHub<#2 (reply in thread)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/BETVUAP3OT5H6VVKLIHDHI3YJDD6LAVCNFSM6AAAAAAV2WPH5GVHI2DSMVQWIX3LMV43SRDJONRXK43TNFXW4Q3PNVWWK3TUHM3TQMZVGU2TQ>. You are receiving this because you commented.Message ID: ***@***.***>

[AlbertFernandoF]

Hi,

I’m currently studying the derivation of the Kohn-Sham equations in Chapter 4 and have some difficulties with Equation 4.62:

1. I’m unclear about the origin of the -3Z term. The text mentions it comes from 2 \epsilon, but isn’t \epsilon = -Z^2 /2? Also, i feel like the integral in this equation is challenging to evaluate analytically. Could you also clarify the source of the 2\pi and r^2 factors?
2. When solving dE/dZ = 0, I find the resulting roots do not align with Z = 1.8. Instead, I get Z = 1.25.
3. Substituting Z = 1.8 back into Equation 4.62 does not yield E = -2.7. Instead, I get E = -1.55.

Could you please provide clarification or point me to additional resources to help resolve these issues?

[nguyen-group]

Hi,

Q1: To analyze the integral in Equation 4.62, we need to use integrals in spherical coordinates. Please find the details how to convert the integrals in #3, then you will see why we have the 2\pi and r^2 factor. I noted that we have a typo in Equation 4.62, it should be E = Z^2-3Z-Z^3*(Z+4)/(Z+2)^3.

Q2 and Q3: Please check with the corrected equation 4.62: E = Z^2-3Z-Z^3*(Z+4)/(Z+2)^3. I believe that Z=1.826 is a solution.
I am sorry that I lost my drafts and was lazy, so I used chatGPT to check.

Nguyen

[AlbertFernandoF]

What about the 2\epsilon = Z^2 - 4Z? i still can't grasp where this idea comes from. isnt \epsilon = -Z^2/2?

[nguyen-group]

What about the 2\epsilon = Z^2 - 4Z? i still can't grasp where this idea comes from. isnt \epsilon = -Z^2/2?

\epsilon = -Z^2/2 is energy without Hartree potential V_H, as defined in Eq. 4.10: h(r)\phi(r)= \epsilon\phi(r).
However, in the case of a helium atom, we consider V_H. Thus, \epsilon is defined in Eq. 4.48: [h(r)+V_H]\phi(r)= \epsilon\phi(r).
After several steps of doing the integrals, we can get \epsilon = Z^2/2-2Z.