[QE-users] Linear response after HSE

[Iurii TIMROV]

Dear Corina,


> I've tried running hp.x after HSE, and I haven't had any luck.


The HP code with hybrid functionals is not implemented/compatible. Do you want to compute the Hubbard U parameter on top of the HSE ground state? Note that one uses either DFT+U (typically with LDA or GGA functionals) or hybrid functionals (e.g. HSE06). DFT+U and HSE06 both correct self-interactions errors; use one or the other. You can find some discussion in this paper (see Sec. II) https://arxiv.org/abs/2203.15732


> So I did a linear response, using the ground state of HSE, but the results don't look right.


In the HP code there is a check. The code will stop if one tries to use it with hybrid functionals.


> is it correct to make a linear response after HSE?


If you refer to HP, then the answer is "No". If you refer to PH, then the answer is "Yes, but it is not implemented". If you refer to TDDFPT, then the answer is "Yes". Note that HP, PH, and TDDFPT are all linear response codes.


HTH


Iurii


--
Dr. Iurii TIMROV
Senior Research Scientist
Theory and Simulation of Materials (THEOS)
Swiss Federal Institute of Technology Lausanne (EPFL)
CH-1015 Lausanne, Switzerland
+41 21 69 34 881
http://people.epfl.ch/265334
________________________________
From: users <users-bounces at lists.quantum-espresso.org> on behalf of Corina Urdaniz <urdaniz.corina at qns.science>
Sent: Tuesday, July 19, 2022 5:02:42 AM
To: Quantum ESPRESSO users Forum
Subject: [QE-users] Linear response after HSE

Dear all,

I've tried running hp.x after HSE, and I haven't had any luck. So I did a linear response, using the ground state of HSE, but the results don't look right. Basically my question is: is it correct to make a linear response after HSE? Maybe I am forgetting some important physical concept.

More details: I tried it in two different systems: V-H (dimer) and a molecule in vacuum. In both, I did a linear response using the ground state from GGA and from HSE. The results from GGA are expected, but in the case of HSE when I plot the number of occupations vs. alpha, I get 2 lines that are parallel or do not intersect at alpha.

Thank you very much, I appreciate any comment that can help me understand what is going on.


Corina Urdaniz
IBS Center for Quantum Nanoscience
Seoul, South Korea
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