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

[Peter Blaha]

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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> 
> -- 
> ------------------------
> 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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-- 
Peter Blaha, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300          Email: peter.blaha at tuwien.ac.at
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