CCL: DFT14poll



I also think the poll has value in discerning trends, especially new funtionals to appear on the list and ones that have fallen down or off.

Steven


On Mon, Jun 2, 2014 at 9:17 AM, Abrash, Samuel sabrash!^!richmond.edu <owner-chemistry]=[ccl.net> wrote:

Sent to CCL by: "Abrash, Samuel" [sabrash..richmond.edu]
I think people are taking the words "popularity contest" too seriously. ÂIt's just a poll to find out what members of this listserve, who are mostly computational chemistry professionals, are using. ÂI agree that the absence of "why" makes this somewhat less useful. ÂHowever, I think it's useful because if I see a functional that I don't know about used widely, I'm going to investigate it. Â(Note not blindly use it, but investigate it.) ÂStill the why is a useful bit of information. ÂFor Âexample, I use M062X for many of my calculations now, and if asked why, I'd say "because reviewers insisted that it's better for complexes than PBEPBE even though my results come out the same with either functional, and I wanted my paper published."

Best,
Sam

-----Original Message-----
> From: owner-chemistry+sabrash==richmond.edu . ccl.net [mailto:owner-chemistry+sabrash==richmond.edu . ccl.net] On Behalf Of Laidig, Bill laidig.wd(_)pg.com
Sent: Sunday, June 01, 2014 8:45 PM
To: Abrash, Samuel
Subject: CCL: DFT14poll


Sent to CCL by: "Laidig, Bill" [laidig.wd=pg.com] I strongly disagree with this position. ÂThere are many scientifically valid reasons to know which functionals are most popular among theoretical and computational chemists (who, I am assuming, are the bulk of this mailing list). ÂFor example:

1. Even if a functional is clearly inferior to another, if it is used much more in real calculations then there may be several reasons to use the inferior function:
  Âa. It is likely more widely implemented meaning you have a wider choice of programs
    Âto use and ways to validate that the calculations were Âperformed correctly.
  Âb. Wider use means that there is a larger statistical pool of data for assessing accuracy,
    Âetc. ÂThis is often much more important than using a marginally better method. ÂWe
    Âsee this in the long-term popularity of methods such as HF/3-21G, and B3LYP/6-31G*.
2. Highly accurate, but arcane theoretical methods make communication of results difficult outside the expert community as the reader has little basis for assessing the quality of results. ÂI learned this the hard way in my career in industry.

Most users of computational chemistry want to know what small handful of methods can be applied broadly to large classes of problems. ÂAs experts, we are the group that is defining the next generation of standard methods so I find it very useful to know in what directions we are heading. ÂLearning why we are using functionals can also let the developer of the "next big thing" know when their efforts to publicize and promote their methodology has fallen short Âand inspire them to better efforts in the future.

Bill Laidig

-----Original Message-----
> From: owner-chemistry+laidig.wd==pg.com^ccl.net
> [mailto:owner-chemistry+laidig.wd==pg.com^ccl.net] On Behalf Of Robert
> Molt Jr r.molt.chemical.physics!=!gmail.com
Sent: Sunday, June 01, 2014 3:07 PM
To: Laidig, Bill
Subject: CCL: DFT14poll


Sent to CCL by: Robert Molt Jr [r.molt.chemical.physics]_[gmail.com]
Sirs and Madames:

A "popularity contest" is anathema to science. ÂThe world should not weight the opinion of Rodney Bartlett and Robert Molt equally in coupled cluster theory.

Perhaps we should take a poll on what people think the first spherical harmonic is? ÂOr take a poll on whether Planck's constant is too small?

Evidence and and logic drive science.

-Robert Molt

On 06/01/2014 12:26 PM, VÃctor LuaÃa Cabal victor,fluor.quimica.uniovi.es wrote:
> Sent to CCL by: =?iso-8859-1?Q?V=EDctor_Lua=F1a?= Cabal
> [victor-.-fluor.quimica.uniovi.es]
> On Sun, Jun 01, 2014 at 06:01:52AM +0000, Rzepa, Henry S h.rzepa:http://imperial.ac.uk" target="_blank">imperial.ac.uk wrote:
>> Can ÂI suggest that in future this poll be extended to indicate WHY any person indicates they ÂLIKE Âa functional? As we all know, the choice of functional so often depends on what the property of interest is.
>>
>> I suggest initially a relatively short controlled list of properties,
>> which can then be extended by Ââcrowd sourcingâ. Properties ÂI have
>> in mind might be eg
>>
>> 1. Reaction barriers
>> 2. Normal mode analysis
>> 3. Chiroptical properties
>> 4. Hydrogen bonds
>> 5. Excitation energies
>> 6. Main group elements
>> 7. Transition metals
>> 8. Relativistic elements
>> 9. NMR shieldings, NMR couplings
>> 10. etc
>>
>> That way, we could find out eg the most liked functional for eg
>> looking at hydrogen bonds. ÂThat would be enormously helpful to
>> anyone looking to study eg hydrogen bonds.
> Dear Prof. Rzepa,
>
> I have a deep respect for your work, that I use to love, but in this
> case I dislike strongly the idea of deciding the use of a functional
> by popularity. There are plenty of examples in which the most popular
> route was not the best, just the easiest. It took decades, in many
> cases, to turn back wrong but popular decisions. Two candidates should
> be advised to create a safe road: the easiest AND the the best
> founded. Notice that the most popular is not in my list. Popularity
> can be obtained by well studied techniques that have nothing to do
> with any real measurement of quality.
>
> As for your list of properties it is very useful and I will keep it
> carefully.
>
> Best regards,
> Â Â Â Â Â Â Â Dr. VÃctor LuaÃa
>
> --
> Â Â Â Â Â \|/
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> ! Departamento de QuÃmica FÃsica y AnalÃtica  !
> ! Universidad de Oviedo, 33006-Oviedo, Spain  !
> ! e-mail:  victor*fluor.quimica.uniovi.es   !
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