B3LYP issue: AGGAC vs. ALDAC

[kich2018]

While I looked through a set of commands which has to be included for each of hybrid functionals, I found some weird information.

VASP wiki site suggests us to use the following commands for PBE0 functional.
LHFCALC = .TRUE.
AEXX=0.25, AGGAX=0.75, AGGAC=1.0 and ALDAC=1.0
GGA = PE

Most of other hybrid functionals (HSE03, HSE06) are also suggested to use AGGAC=1.0 and ALDAC=1.0.
I could guess from this information (AGGAC=1.0; ALDAC=1.0) that AGGAC means just a gradient correction itself introduced to LDA.
Therefore, in my opinion, GGA (AGGAC=1.0 and ALDAC=1.0) contains the contributions of both the electron density and the gradient of the electron density to the correlation energy.
In contrast, AGGAC=1.0 and ALDAC=0.0 indicates the contribution of the electron density gradient only to the correlation energy.
I think that this is the main reason why VASP wiki suggest AGGAC=1.0 and ALDAC=1.0 instead of AGGAC=1.0 and ALDAC=0.0.

However, my understanding constructed on the basis of the afore-mentioned information has been messed up due to the commands for B3LYP.
VASP wiki site suggests us to use the following commands for B3LYP functional.
LHFCALC = .TRUE.
GGA = B3
AEXX = 0.2
AGGAX = 0.72
AGGAC = 0.81
ALDAC = 0.19

I have no idea of why the site suggests ALDAC=0.19 instead of ALDAC=1.0, although B3LYP uses the combination of the purely electron density-based correlation energy (LDA) of 19% and the gradient-corrected LDA correlation energy (GGA) of 81% by definition.
I think AGGAC=0.81 and ALDAC=0.19 means LDA of 19% and just gradient correction of 81%.

[martin.schlipf]

Thank you for pointing out this inconsistency. Fortunately, it is only an inconsistency in the user interface, because the routines internally use different methods to evaluate the xc energy. We verified both functionals against an implementation in Gaussian with a high level of agreement.

So you need to use the functionals as they are written on the wiki, even if that is not internally consistent.