As stated before I want to try out custom-defined functionals. Besides the question about B3LYP itself, there is another related question.
Short excerpt:
$$\text{XC-Functional}=a E_x^\text{local}+(1-a)E_x^\text{HF}+b E_x^\text{non-local}+c E_c^\text{non-local}+(1-c) E_c^\text{local}$$
The Gaussian documentation for DFT inputs specifies how one could change the amounts of each "sub-functional" by using the IOp-Statements through:
IOp(3/76=mmmmmnnnnn) IOp(3/77=mmmmmnnnnn) IOp(3/78=mmmmmnnnnn)
Where
mmmmm
andnnnnn
will get divided by 10000 and3/76
=$P_1P_2$,3/77
=$P_3P_4$ and3/88
=$P_5P_6$. Those $P_{1,..,6}$ values are part of the following equation, which is a modified version of the equation above.$$\text{XC-Functional}=P_2 E_X^\text{HF} + P_1 \left(P_4 E_X^\text{Slater} + P_3\Delta E_x^\text{non-local}\right) + P_6 E_C^\text{local} + P_5 \Delta E_C^\text{non-local}$$
Now Gaussian's description site about DFT tells that one simply has to choose one exchange and one correlation functional, i.e. B and LYP. But then B would be used for $E_x^\text{non-local}$ and LYP probably for $E_c^\text{non-local}$.
Does that mean, that the $E_c^\text{local}$-part
- cannot be defined,
- is always the VWN functional as in B3LYP, or
- is also the chosen correlation functional?