CCL: Constructive DFT suggestions appreciated
- From: "Lars Goerigk"
- Subject: CCL: Constructive DFT suggestions appreciated
- Date: Tue, 22 Sep 2015 20:17:32 -0400
Sent to CCL by: "Lars Goerigk" [lars.goerigk*|*unimelb.edu.au]
I recommend you read this paper in which Stefan Grimme and I benchmarked nearly
50 methods on a large set of chemically relevant problems.
This paper did not only have a look at the overall accuracy of a method but also
on its robustness, that means how reliable the method is when you change from
one chemical problem to another:
PCCP 2011, 13, 6670.
The general recommendations are:
- The higher you climb on Jacobs Ladder, the more reliable your result is.
- Recommended GGA methods: revPBE-D3, B97-D3
- Recommended meta-GGA methods: oTPSS-D3, TPSS-D3
- Hybrid functionals: PW6B95-D3, M062X-D3
Comment: Yes, also Minnesota functionals need dispersion corrections!
a) This was shown for the M05 and M06 suites of functionals
in ChemPhysChem 2011, 12, 3421.
b) For the latest Minnestoa-type methods (the M11, MN12,
N12, and SOGGA11 suites of functionals), unusual problems around van-der-Waals
minima were reported in J. Phys. Chem. Lett. 2015, 6, 3891.
c) Note that B3LYP-D3 is worse than the average of more than
20 tested hybrids!
- Double-hybrids are the most accurate DFT methods on the market: DSD-BLYP-D3,
Comment: They may need an additional MP2-type term, however, efficient
programs, such as ORCA or Turbomole, make use of the RI approximation to speed
up this step. So overall, double-hybrids are not too costly nowadays.
However, you need at least a good triple-zeta basis set, do
not use double-zeta basis sets for double-hybrids.
- Always use a dispersion correction!
- As for the famous B3LYP/6-31G* model chemistry, its flaws are discussed
JOC 2012, 77, 10824
I hope that helped.
Dr. Lars Goerigk
ARC DECRA Fellow
School of Chemistry
The University of Melbourne
List of my publications:
Follow me on Twitter: https://twitter.com/lgoer_compchem
On 23 Sep 2015, at 7:31 am, Alan Shusterman alan=-=reed.edu
I have read several CCL messages over the past few weeks disparaging a
correspondent's choice of DFT functional (usually B3LYP, but not always) as
being obsolete, useless, or both.
These are perfectly fair opinions to share, but they are not constructive. If
you want to disparage a computational approach, fine with me, but please
recommend at least one better alternative. I would like to learn what you think
I should use, not just what I should not use.
You don't need to cite publications or explain why you prefer a particular
functional. I can look that up once you tell me which functional(s) you think
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