[Wien] A basic question regarding using GGA+U approach

[xavier rocquefelte]

You are right Peter.

Here is a paper of Ceder: https://www.nature.com/articles/npjcompumats20162

It is quite tricky.

Cheers

Xavier

On 11/02/2022 08:50, Peter Blaha wrote:
> Hmm.
>
> Depending on the metal, a hybrid DFT calculation for the metal is as 
> problematic (or even more) that a LDA+U calculation.
> It overestimates itinerant magnetic moments and in addition also 
> affects the "free-electron" like 4s electrons ...
>
> Formation energies (voltages) with correlated electrons are always 
> "tricky". I think Ceder has published a lot of such calculations on 
> voltages including various more or less empirical "tricks".
>
> Eventually, you may try a meta-GGA ....., but this is probably also 
> not very good.
>
> Best regards
> Peter Blaha
>
> Am 2/11/22 um 08:19 schrieb xavier rocquefelte:
>> Dear Shamik,
>>
>> To my point of view using the strategy (1) is not correct. I 
>> understand that B will require a different treatment in ABS2 and pure 
>> B phases.
>>
>> You certainly has no other choice than using hybrid functional for 
>> all calculations ... and then you will be able to compare to the 
>> results of strategy (2).
>>
>> Best Regards
>>
>> Xavier
>>
>>
>>
>> On 11/02/2022 06:40, shamik chakrabarti wrote:
>>> Dear Wien2k users,
>>>
>>>                            I have studied the intercalation of A in 
>>> BS2 to form ABS2. In this calculation, I have used Hubbard U for B 
>>> in BS2, and in ABS2 & I got reasonable voltage.
>>> However, now I want to study the voltage corresponding to the 
>>> conversion reaction; ABS2 + A =2A2S +B. In this case, B is a metal & 
>>> hence to simulate the voltage
>>> (1) Should I need to consider the energy value corresponding to 
>>> GGA+U approach applied to ABS2 or,
>>> (2) Should I need to consider the energy value corresponding to GGA 
>>> approach applied to ABS2
>>>
>>> As A & A2S & B have been simulated using GGA.
>>>
>>> Looking forward to your reply in this regard.
>>>
>>> with regards,
>>>
>>> -- 
>>> Dr. Shamik Chakrabarti
>>> Research Fellow
>>> Department of Physics
>>> Indian Institute of Technology Patna
>>> Bihta-801103
>>> Patna
>>> Bihar, India
>>>
>>> _______________________________________________
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>>> at:http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
>>
>> -- 
>> ------------------------
>> Professeur des Universités de Rennes 1
>> Institut des Sciences Chimiques de Rennes (ISCR)
>> Univ Rennes - CNRS - UMR6226, France
>> https://iscr.univ-rennes1.fr/xavier-rocquefelte
>> ------------------------
>>
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-- 
------------------------
Professeur des Universités de Rennes 1
Institut des Sciences Chimiques de Rennes (ISCR)
Univ Rennes - CNRS - UMR6226, France
https://iscr.univ-rennes1.fr/xavier-rocquefelte
------------------------