Hi community. I want to compare some results between Dalton and Gaussian16. The implementation of B3LYP is different in both programs. Though I know that Dalton has the Gaussian-like B3LYP functional (B3LYPG), the calculation I want to run is not implemented with such functional yet. Hence, I need to change the definition of B3LYP in Gaussian to make it equal to Dalton´s. Here goes both definitions:
Dalton's definition: HF=0.2 Slater=0.8 Becke=0.72 LYP=0.81 VWN=0.19 Gaussian's definition: HF=0.2 Slater=0.8 Becke=0.72 LYP=0.81 VWN3=0.19
According to my understanding, what I need to do is to change the VWN (III) version to VWN (I) version in Gaussian but I was not been able to find the way.
Can you help me with this?
Many thanks in advance.
Not a Dalton user, but I'm fairly sure that it will use the VWN5 correlation functional in its definition of B3LYP.
If you want Gaussian to use VWN5 in a B3LYP calculation, then use the following route line:
# bv5lyp iop(3/76=1000002000) iop(3/77=0720008000) iop(3/78=0810010000)
You will also have to pay attention to basis set, integration grid, integral cutoffs, SCF convergence, and optimization convergence among other things if you want to be able to compare results across different programs....
Also, here is an interesting summary of how things ended up this way ...
http://www.ccl.net/chemistry/resources/messages/2002/05/22.008-dir/
Hi Prof Paton. Thank you so much for your response. I think you are right, or at least I converged to the same conclusion. I need to change the VWN3 to VWN5. Thank you as well for the other recommendations, I will keep them in mind.
Cheers
Federico
https://sites.google.com/site/rangsiman1993/comp-chem/tips-and-tricks/gaussian-b3lyp
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