Talk:Franck–Condon principle

message: please, somebody should explain what dtau means in the integral in the qm derivation  —Preceding unsigned comment added by 164.54.94.95 (talk) 20:29, 11 November 2010 (UTC)
thread_title: Explanation of tau

message: I have added a major expansion to the existing stub in an attempt to bring the Franck-Condon Principle entry to full article standards. There are quite a few improvments that can be made and I will try to work on some in the comming weeks. In particular I think it would be nice to incorporate figures with real data, for example a real data version of figure 2. I someone has some nice data to incorporate please go ahead, otherwise I will try finding something in the literature that can be added under fair use. Somoza 10:51, 3 July 2006 (UTC)
thread_title: Comments

message: Should "Franck-Condon approximation" redirect to here? I've made this redirect already... --HappyCamper 16:48, 19 July 2006 (UTC)
replies: text: I think "approximation" is used instead of "principle" when the author wishes to emphasize the limitations of the assumptions that are used in the Franck-Condon principle.Somoza 09:23, 15 August 2006 (UTC)
thread_title:  Franck Condon approximation 

message: Why is the article buried under stuff which belongs to the harmonic oscillator ?Arnero 08:19, 20 September 2006 (UTC)
replies: text: For example??Somoza 10:32, 20 September 2006 (UTC)
thread_title:  Lemma 

message: What are the next steps for this article? Perhaps we should highlight some computational approaches for handling large FC systems? --HappyCamper 15:35, 25 January 2007 (UTC)
thread_title:  Next steps 

message: I changed the ratings because I don't think that Wikipedia articles on any of the sciences will get any better than this one. Further it is well-known that the Franck-Condon principle is of utmost importance in spectroscopy. I realize that these two sentences are highly subjective, but (i) at least I have read the article and (ii) I bothered to write this (short) motivation.--P.wormer 00:59, 11 April 2007 (UTC)
replies: text: The next highest rating beyond B is GA (Good Article). See WP:GOOD for information about the nomination and review process. --Kkmurray 19:11, 1 September 2007 (UTC)
thread_title:  Ratings 

message: The Russian anonymous 212.192.238.23 deleted half of van der Waals equation. Looking at what (s)he further did I saw that (s)he removed some didactic and nice LaTeX stuff from the present article. Again without a single word of motivation! That is why I reverted. Please anon 212.192.238.23  explain why you find it necessary to delete stuff. Remember Wiki is not paper,
size is not an issue!--P.wormer 08:07, 8 June 2007 (UTC)
thread_title:  Reversal of edit by 212.192.238.23  

message: In the section quantum mechanical formulation the term "orbital" is used several times in contexts where I would use "spatial". Both terms are in contrast to "spin". However, for me "orbital" often implies a one-electron picture, which is here not necessarily the case. So I changed orbital to spatial or electronic in some places. But not everywhere, because for instance  the term "spin-orbit coupling" does not necessarily imply a one-electron picture. Thinking about it, it occurs to me that QM terminology is not really unambiguous about the terms "space", "orbit" and "orbital" (to distinguish from spin). Further I assumed that everywhere in the article spin relates to electronic spin and not to nuclear spin.--P.wormer --P.wormer 15:34, 17 June 2007 (UTC)
thread_title:  orbital v. spatial 

message: In the introduction, it is stated that "Vibronic transitions are the simultaneous changes in electronic and vibrational energy levels of a molecule due to the absorption or emission of a photon of the appropriate energy." However, a photon is not the only energy packet that can cause these transitions. Is it better to change the word "photon" to "energy packet"? Erwin (talk) 09:55, 29 July 2008 (UTC)
thread_title:  Absorption/emission of energy packet 

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thread_title: File:James-franck-fig-1.jpg Nominated for Deletion

message: I do not think it is correct to write the electronic wavefunction as a product of spin and spatial parts:
\psi_e \psi_s
For general many-electron wavefunctions this is not possible. Spin is constructed as a linear combination of different Slater determinants not as a product with a spin-function.
An important consequence of this is the following: If we want to look at absorption into Triplet states or at phosphorescence, we can't just look at the spin and spatial parts separately. Computing the intensities for such "spin-forbidden" processes is significantly more involved. One has to to a summation over all the individual Slater determinants involved.
Felixp84 (talk) 14:06, 12 November 2018 (UTC)
replies: text: You are thinking of an approximate wavefunction, ultimately derived from an independent particle model. Here the starting point is an exact eigenfunction \psi_{\rm ev}\psi_{\rm s } of a spin-free, N-electron, K-nucleus Hamiltonian. --P.wormer (talk) 23:13, 12 November 2018 (UTC)
replies: text:  Thanks for the clarification. But I think it would make sense to explain where this really comes from. The separation of electrons and nuclei derives from the Born-Oppenheimer approximation. Is there an analogous approximation or even an exact statement that says that one can separate the spatial and spin electronic coordinates in the same way? It would be good to mention this -- Felixp84 (talk) 12:40, 13 November 2018 (UTC)
replies: text:  Because the Hamiltonian does not contain electronic- or nuclear-spin interactions the exact wavefunction can be factorized in a spatial factor—containing electronic and nuclear spatial coordinates—, an electronic-spin factor, and a nuclear-spin factor. And you're exactly right, further factorization of the first part requires the BO approximation. If I had written this article, I would have left out the electronic spin function \psi_{\rm s }, in the same way as as the nuclear spin function is left out. --P.wormer (talk) 14:56, 13 November 2018 (UTC)
thread_title:  Spin function