Defining the Turbomole named BP86 functional in Gaussian [closed]








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According to Turbomole, the BP86 density functional has the following definition:


$$
\mathrm{Exchange = LDA + B88\\
Correlation = LDA(VWN(V)) + P86}
$$


What is the equivalent definition in Gaussian using `IOp` keywords? 




From the Gaussian 09 manual:



> 
> User-Defined Models. Gaussian 09 can use any model of the general form:
>  P2EXHF + P1(P4EXSlater + P3ΔExnon-local) + P6EClocal + P5ΔECnon-local
> 
> 
> The only available local exchange method is Slater (S), which should be used when only local exchange is desired. Any combinable non-local exchange functional and combinable correlation functional may be used (as listed previously).
> 
> 
> The values of the six parameters are specified with various non-standard options to the program:
> 
> 
> * IOp(3/76=mmmmmnnnnn) sets P1 to mmmmm/10000 and P2 to nnnnn/10000. P1 is usually set to either 1.0 or 0.0, depending on whether an exchange functional is desired or not, and any scaling is accomplished using P3 and P4.
> * IOp(3/77=mmmmmnnnnn) sets P3 to mmmmm/10000 and P4 to nnnnn/10000.
> * IOp(3/78=mmmmmnnnnn) sets P5 to mmmmm/10000 and P6 to nnnnn/10000.
> 
> 
> For example, IOp(3/76=1000005000) sets P1 to 1.0 and P2 to 0.5. Note that all values must be expressed using five digits, adding any necessary leading zeros.
> 
> 
> Here is a route section specifying the functional corresponding to the B3LYP keyword:
> 
> 
> `#P BLYP IOp(3/76=1000002000) IOp(3/77=0720008000) IOp(3/78=0810010000)`
> 
> 
> The output file displays the values that are in use:
> 
> 
> 
> ```
> IExCor=  402 DFT=T Ex=B+HF Corr=LYP ExCW=0 ScaHFX=  0.200000
> ScaDFX=  0.800000  0.720000  1.000000  0.810000 
> 
> ```
> 
> where the value of ScaHFX is P2, and the sequence of values given for ScaDFX are P4, P3, P6 and P5.
> 
> 
> 


For BP86 specified normally, this looks like:



```
IExCor=  404 DFT=T Ex=B Corr=P86 ExCW=0 ScaHFX=  0.000000
ScaDFX=  1.000000  1.000000  1.000000  1.000000

```

Those 3 IOps don't completely define the functional, however, `IOp(3/74)` is also needed. See the `IExCor` field, which corresponds to Becke 1988 exchange (400) combined with Perdew 81 + Perdew 86 correlation (4).


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