Talk:Morse/Long-range potential

Residual use of the Morse potential

It was stated by user: https://en.wikipedia.org/wiki/Special:Contributions/87.77.234.110 that the Morse potential might still be used for fits to spectroscopic data. However, a search on Google scholar: https://scholar.google.com/scholar?as_ylo=2011&q=morse+potential&hl=en&as_sdt=0,5 does not show any empirical potentials fitted to the Morse model since the MLR was introduced in 2009. Rosen-Morse and "Generalized Morse" are shown, but not plain Morse. Dr. Universe (talk) 11:57, 18 April 2015 (UTC)

Undefined terms

The functions presented in this article in the Function section do not have any of their terms defined. See: https://en.wikipedia.org/wiki/Wikipedia:Manual_of_Style/Mathematics for standards of presentation. Leperflesh (talk) 18:44, 5 November 2019 (UTC)

Good point, $r_{e}$ was defined but not ${\mathfrak {D}}_{e}$ (Depth of the potential at equilibrium). I'll look at the others too. Dr. Universe (talk) 21:27, 25 May 2021 (UTC)

2007 paper

@JoelleJay:,@TheLawGiverOfDFT::

• Eq 14 of the 2007 paper is incorrect if you work out the calculus as $r\rightarrow \infty$, and I can't even see how it could be consolidated or compatible with the description in this wiki article which follows the later articles (2009 and beyond).
• Eq. 12 is also incorrect, for a completely independent reason. It's missing the quadratic term from the Wikipedia article, which means the MLR which is supposed to be Morse-like when $r\approx \infty$ and have the correct long-range when $r\approx \infty$ (for example C6/r^6), unfortunately does not have the correct long-range as you will get C6 + [some other wrong stuff...].
• So the authors of this paper "thought" they had created a truly Morse/long-range potential, but due to miscalculations in Eq. 12 the long-range part was not correct.
• I cannot even see this 2007 paper on LeRoy's Google Scholar page, so it would appear that with the above errors LeRoy does not endorse the paper.
• Furthermore, the end of the 2007 paper expresses hopes that the MLR can become even more realistic (allowing more complicated u(r) functions, damping functions, more than two C coefficients, etc.).
• All of the above were fixed in the 2008 and 2009 papers: the 2008 one pointing out the problem and how to fix it, and the 2009 ones both implementing the more complicated u(r) incorporating 2-state coupling. The 2011 paper (Dattani & LeRoy, Journal of Molecular Spectroscopy) went as far as 3-state coupling and I've never seen anyone go beyond 3 states.
• Notice Eq. 11 of the 2007 paper is also not the same in the subsequent papers starting with the 2009 conference paper which you can download from the Ohio State University archive (I believe I gave the page number in the AfD discussion, but it might have put <-- --> around it because those discussions started getting very long!).
• There's more differences between the 2007 paper and the later ones, as there's no room for the q parameter and the y variable is centered around a fixed constant re rather than a variable r_reff.

So while it makes sense to have the 2007 paper cited in the article (indeed it was cited, just not in the opening part, I really wrote the article with the 2008 version of the MLR potential in mind, since that's what other authors such as Stolyarov, Tiemann, and the ab initio people use when they report results with the MLR. I didn't know about the 2008 paper at the time of writing the article (I was forced to dig that one up due to the AfD discussion with Joelle), so I cited the 2009 paper and named the two theorists, plus Coxon since he introduced a new variable (m) and called it the MLR3 in 2010, but now 8 years have passed since I wrote the Wiki article in 2013 and the MLR3 isn't really being used, so Coxon doesn't really need to be named. I've corresponded with Coxon many times and as recently as 2019, and in 2020 with one of his long-time co-authors. I did a lot of research before making this article.

TheLawGiverOfDFT: I see you wrote out your suspicions about who a user is "in real life" in the edit summary, and I just wanted to let you know that I've got in trouble for doing that before. Everything here is publicly available and permanent in the revision history, so we just have to be a bit careful about everything we write, especially allegations before having definitive proof. Also the public doesn't know who "TheLawGiverOfDFT" is, but the Wiki admins have been known to figure things like this out, especially if it turns out that Ball State University email address in this investigation involving you turns out to establish any connection. So allegations without proof are not only discouraged on Wikipedia but some admins can use browser cookies, IP addresses, and further investigative efforts to find out who made them. Sorry if this was a bad first experience on Wiki (sending an article to AfD as your first Wiki edit, is quite a bold move though!) but you're learning quickly and I've seen many people with a "rough start" go on to become valuable contributors. Dr. Universe (talk) 21:27, 25 May 2021 (UTC)

c-state of Li2

@TheLawGiverOfDFT: For the sentence "Two years later it was found that Dattani's MLR potential was able to successfully predict the energies in the middle of this gap" you changed it from "Dattani's MLR" to "the MLR" and wrote "Dattani is relevant to this article, but suspected COI on his addition's when other authors are not addressed. Dr. Universe may be Nike Dattani". I totally understand that it would look bizarre and appear to be due to a COI, if the article says the function was first defined by LeRoy, Dattani and Coxon, then later it says "Dattani's MLR" without naming LeRoy and Coxon. However in that sentence we're not talking about "the MLR" as in "the MLR model" (which is how the wording was in the previous sentence), but we are talking about the 'specific' MLR potential (along with the specific values for each of the optimized parameters) from the paper on which Dattani was first author. The following point (also written by me) actually only mentioned LeRoy's name and not Dattani's at all. In retrospect it would have been better to put "Dattani 'et al.'" rather than just Dattani, but Dattani was first author so gets named before LeRoy here, and Coxon doesn't get mentioned. Dr. Universe (talk) 00:25, 26 May 2021 (UTC)

• If you feel it appropriate to reintroduce it more clearly, that should be fine in my opinion. 00:29, 26 May 2021 (UTC) — Preceding unsigned comment added by TheLawGiverOfDFT (talk • contribs)
  • @TheLawGiverOfDFT: We had an edit conflict since we both tried to comment at around the same time. Here's what I wrote: I'll leave it up to you for now, to decide if you want to change it back to just "Dattani's" or "Dattani and LeRoy's" or "Dattani 'et al.s". It's hard to know what I was thinking 8 years ago, but I may have felt the latter two options were too "bulky" (and I still do). In the following point it's okay to say "LeRoy 'et al.' constructed" because we don't have to put the apostrophe and \'s\' after 'et al.', and since I was mentioning LeRoy's name in the next bullet point, I thought "Dattani's" would look best overall. The citation 'clearly' shows who is an author and who is not, and combined with LeRoy's name being mentioned in multiple other parts of the paper 'no one is missing out on being mentioned' if it says "Dattani's MLR" but I'll leave it to you how you want to change it to reflect that it's a specific MLR function including all parameters set numerically rather than being variables like in the 'general' definition of the MLR model. Dr. Universe (talk) 00:35, 26 May 2021 (UTC)