Talk:Quantum chemistry

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Query[edit]

Maybe some explanation about the basics of ab initio calculations should be here (or linked here). And the self-consistent-field scheme could be turned into a link.

4lex


A couple questions before I edit: 1) is there a specific reason why Density functional theory is not included? It's probably the most widely used quantum theory at present 2) Why is Dogonadze's work specifically mentioned in this overview? He doesn't have anywhere near the stature of anyone else mentioned in the article, and he is far from the only person to apply quantum chemistry to a specific class of problesm, nor is he the most well-known person to do so. Salsb 14:58, 22 July 2005 (UTC)

I think the answer to all your questions is the same: this page is simply not cared for. Not many people read this page, and even fewer edit it. I have been wanting to update/imporove/expand this article, but I have serious time restraints. So feel free to edit if you feel the need and have the time. I may get arounf to it sometime soon, too. Karol July 8, 2005 15:39 (UTC) (P.S. always do sign your posts, please)

MD[edit]

I don't think Molecular Dynamics should have such coverage, as in its own section, in this article. MD in itself doesn't have much to do with quantum mechanics, and its concept is based on classical Newtonian dynamics. So maybe the section should be renamed and/or rewritten a bit? Karol 07:41, July 23, 2005 (UTC) P.S. Please remember this is just a general wondering... it seems to me that maybe a more appropriate motif would be Nuclear motion or something else that is clearly related to the Born-Oppenheimer approx., which is the initial reason why electronic structure and nuclei are considered separately in quantum chemistry. And then, MD is a plausible extension of QC for considering nuclear motion, but also molecular mechanics and so forth. What do other people think? Karol 08:00, July 23, 2005 (UTC)

I think having a section, albeit shorter, on ab initio molecular dynamics makes sense, since it is a growing aspect of quantum chemistry. Although the sections at present aren't about MD, rather they are on reaction rate theory. One can obtain the parameters for these theories from molecular dynamics, but you don't have to. 13:14, 23 July 2005 (UTC)
This is not a growing aspect of quantum chemistry this is a very important aspect and that from the beginning of quantum chemistry on (see references in this article)! Chemistry is the science of molecules and of their transformations! Not only of their structures. This is therefore not surprizing that, since the beginning (1927), quantal chemists - all physicists by the way - have tried use quantum mechanics to model reactivity.
You are thinking of what would be called chemical dynamics or reactive dynamics. See the molecular dynamics entry for a rough but reasonable definition. Salsb 13:07, 25 July 2005 (UTC)
The problem is the slang word "MD-Molecular Dynamics" which is in fact restricted to classical molecular dynamics. But molecular dynamics has allways been used for all kind of dynamics that you call "chemical dynamics or reactive dynamics". This is just recently (when the field of classical MD developed that this happened. One sometimes hear Quantum Molecular Dynamics to stress the distinction but basically molecular dynamics is the science of the motion of nuclei. Independently of the method used.
MD is far from a slang word, it has been established in the literature for quite a few years now. Also MD need not be classical, there are now quantum molecular dynamics methods, both for the nuclei and the elections. Furthmore, MD has been around for at least 25 years, so I would not call it recently either. I have several texts on, at least partially, reactive dynamics on my bookshelf, and neither my recollection, nor a quick glance through them shows molecular dynamics being used in the manner you wish to use it. I'll assume your usage is old though. There of course is overlap between molecular dynamics and chemical dynamics, e.g. reactive molecular dynamics, Salsb 14:15, 25 July 2005 (UTC)
I think what is very fruitfull in writing an encyclopedia is to speak with people from different communities and try to find a common language. I know many people who pretend they are doing molecular dynamics but are doing what you call chemical dynamics. According to the definition provided by the article molecular dynamics quantum molecular dynamics is not molecular dynamics but let us call this chemical dynamics. I think we can find a compromise by replacing molecular dynamics in my sense with chemical dynamics. Do you agree that molecular dynamics is a subfield of chemical dynamics? If not than which name do you give to the science concerned with the movement of the nuclei in general? --131.220.68.177 14:35, 25 July 2005 (UTC)
I disagree with calling molecular dynamics a subfield of chemical dynamics, as molecular dynamics rarely concerns itself with reactivity, whereas chemical dynamics almost always does. There is no name for the field concerned with movements of nuclei in general. Incidently, the article on molecular dynamics does discuss the use of quantum models briefly; likely too briefly. Salsb 17:28, 26 July 2005 (UTC)
The quantum models referred to in molecular dynamics are model for the interaction potential! Not for the motion of the nuclei. I think the problem is that in contradistinction with what the normal use of the English language suggests : quantum molecular dynamics and semiclassical quantum dynamics are not subfields of molecular dynamics (MD) in the present use of these words. So I think my new suggestion take this fact into account. --81.209.204.128 21:22, 26 July 2005 (UTC)
I think this is a conceptual problem. Quantum chemistry is concerned with solving the Schroedinger equation for the total molecular Hamiltonian and not only of the electronic molecular Hamiltonian. Spectroscopists are measuring the energy levels of the molecular Hamiltonian and not only of its electronic term. It is therefore important to present on an equal (formal) footing the electronic structure and the molecular dynamics. But I understand that, since the community concerned with molecular dynamics is much less extended that the one concerned with electronic structure, the part of the article on dynamics should be also less extended. BUT this must be done by extending the electronic structure part and NOT by cutting into the dynamics part!
On the other hand, the electronic structure part of the problem MUST be quantal. This is not because molecular mechanics seems at first glance to be purely classical that it is. Molecular mechanics tries to mimic the quantal properties (the potential surfaces) with classical forces but this is usefull only because it is very difficult to compute potential energy surfaces with more than 4 degrees of freedom. On the other hand the traditionally -- well this tradition is in fact very young -- chosen name Molecular Dynamics (MD) is a bit confusing because it is usually restricted to the application of Newton's laws of motion to the movement of the nuclei on potential energy surfaces (which can be in turn obtained from the molecular mechanical approximation). But basically molecular dynamics is the theory of the dynamics of the nuclei independent of the method used : quantal, semiclassical, classical, or even statistical!
Reaction rate theory is a quantum theory applied to the movement of the nuclei in chemistry. It is therefore a branch of molecular dynamics. Of course the parameters must not come from electronic structure calculation but the conceptual point -- the important one from the encyclopedic point of view -- is that they can! Just as potential energy surfaces which can be fitted to microwave spectroscopical data.
sorry, reaction rate theory is not a branch of molecular dynamics. Please look through the references provided on the molecular dynamics article and that will be clear. Salsb 13:07, 25 July 2005 (UTC)
It is a branch of what then? Does is stand alone? If you define molecular dynamics as the science concerned with the movement of the molecular nuclei, it is. Even if nowadays classical MD people do not consider it as a part of their field of research.
Here in this article I have followed the tradition developed by my predecessors and focused on the historical aspects only. Who has been the first to do what. I think this is a good point of view because nowadays (i.e. since the 1970's) it is not possible anymore to distinguish quantum chemistry from computational chemistry. I therefore think the quantum chemistry article should focus on the quantal aspects of chemistry which are not linked (or have not been influenced) by the coming up of the computer techniques. Of course I understand there are methods usefull for chemistry which have nothing to do with quantum chemistry but nevertheless require computer implementation. I am not a specialist in this domain but why not making a new section in the article of computational chemistry?
Another point of view (which is as good as the preceeding) is the following. One could move all quantal techniques presented in the article computational chemistry to this article. One should then name the first part "historical introduction or the birth of quantum chemistry" and the second part "contemporary or modern techniques". One could even mix all sections together. OK. That's a good point too but then one would have problems with the classical molecular dynamics community which shall not find it good to find its work under the title "quantum chemistry". The other problem is that there would not be more or less anything left in the article "computational chemistry" except a link to "quantum chemistry" and something looking like a stub which would require much expansion like the "theoretical chemistry" article. So if you think this is the good way to do it. Please be bold : do it! :-) --131.220.68.177 09:05, 25 July 2005 (UTC)

Chemical dynamics[edit]

I didn't think chemical dynamics existed as a concept because I come from a department called "molecular dynamics" in its old sense. I have looked on the internet and found that indeed some people use the term chemical dynamics. So I think we could use this term to distinguish "molecular dynamics" from "MD". --131.220.68.177 13:56, 25 July 2005 (UTC)

What is the science of the "motion of the nuclei"?[edit]

Well I have reverted the last version because we have first to agree on a name for the science of the "motion of the nuclei".

I had suggested "molecular dynamics" but this is a reserved name for newtonian molecular dynamics. So I thought "chemical dynamics" would be good but then one editor wants to restrict this concept to the science of "chemical rates".

I am awaiting your advice before editing further on. --131.220.68.177 15:02, 25 July 2005 (UTC)

I propose simply the motion of nuclei :) Karol 15:08, July 25, 2005 (UTC)
The term the motion of nuclei is sounding a bit too much as if nuclei were moving according to the laws of Newton only. --131.220.68.177 15:15, 25 July 2005 (UTC)
Well, how about paraphrasing to nuclear motion? Karol 17:33, July 25, 2005 (UTC)

Wow![edit]

I am so impressed with how this article has progressed - I stopped looking at it a few months ago, and now, look at it today! Congrats to everyone who has effort into making it better! --HappyCamper 01:28, 19 December 2005 (UTC)

Origen of the field of quantum chemistry[edit]

In a public lecture at Cal Tech in 1960, Linus Pauling explained that he had intended to teach a physics course on bonding, but that, even though he had been appointed professor of physics as well as of chemistry, his boss was the chemistry department chairman who discouraged his teaching a physics course. As a result of this, he "included the material in his [chemistry] course on "the nature of the chemical bond". David R. Ingham 04:58, 30 January 2006 (UTC)

Equivalent name for quantum chemistry(?)[edit]

Is the term quantum chemistry equivalent to molecular quantum mechanics?--86.125.174.102 (talk) 21:14, 25 November 2014 (UTC)

Image:LinusPauling.jpg[edit]

What happened to that picture of Linus Pauling that used to be on the top part of this article?--71.249.23.233 14:55, 8 October 2006 (UTC)

Delisted GA[edit]

This article has been removed from the GA list due to lack of inline citations. Tarret 15:47, 15 March 2007 (UTC)

Difference from Physical Chemistry[edit]

Hello. I was just wondering what the difference between physical chemistry and quantum chemistry is? —Preceding unsigned comment added by 165.91.166.244 (talk) 21:12, 15 April 2010 (UTC)

If you look at any of the many texts called "Physical Chemistry", you will see that they contain much material that is not Quantum Chemistry and that the latter is often just a section of the book. --Bduke (Discussion) 22:03, 15 April 2010 (UTC)
I think the article would benefit from a better discussion of the relationship between quantum and physical chemistry. I was under the impression that quantum chemistry is considered a subfield of physical chemistry, and Bduke's response implies that this is the case. The opening paragraph of this article states, "[Quantum chemistry] has a strong and active overlap with the field of atomic physics and molecular physics, as well as physical chemistry," which suggests that quantum and physical chemistry are distinct disciplines. Myceteae (talk) 03:27, 10 August 2010 (UTC)

Reason for hatnote[edit]

Every sentence in the opening paragraph is misguided. QFT appears in only a minute part of literature of chemistry. Electronic structure of molecules should be mentioned before reactivity. "Border" is vague -- maybe "studied by scientists trained in chemistry, physics and mathematics". Needs complete rewrite. Michael P. Barnett (talk) 20:20, 30 January 2011 (UTC)

New lede[edit]

I am trying to edit the article about Charles Coulson. This has to refer to topics that include Quantum chemistry. I have put in a new lede with which I am comfortable as a former student of Charles. I have published on quantum chemistry for the past 60 years. I do not speak for the world of quantum chemistry, and I would welcome informed editing. I cannot become involved in editing the material already in place. I hope the tactic that I have adopted, by putting the previous lede under "An alternative approach" is a reasonable compromise. What happens to my lede will provide data for a study on the extent to which the Wikipedia approach allows articles based on professional knowledge. Michael P. Barnett (talk) 14:39, 3 February 2011 (UTC)

Sections removed April 28[edit]

Absent comments on my earlier comments on old lede that I moved down to the section "An alternative approach" (see above) I deleted it.

Absent justification of the section on quantum field theory I deleted it. No WK verifiability was provided of "The application of quantum field theory (QFT) to chemical systems and theories has become increasingly common". The only specific provided is the photomagneton. A Web of Science search using this as the key found 14 papers published in the mid 1990s. A cursory inspection of the articles on nuclear chemistry, sonochemistry, astrochemistry did not find mention of quantum field theory, but even if it did verifiably, I thought WK requires each article to stand on its own feet for verifiability.

I would be glad to see useful information in the two deleted sections reinstated with appropriate references if verifiableMichael P. Barnett (talk) 10:43, 28 April 2011 (UTC)

Removing the template[edit]

I think that this paper is not misleading and the template can cause fear in the readers, although the article seems OK. The definition in the abstract is correct. OFLOMENBOM (talk) 17:43, 17 June 2011 (UTC)

Is Quantum chemistry a branch of physics or of chemistry?[edit]

Please see recent edits and discussion at User talk:Elie.nasrallah. If my revert is reverted by him, he will have breached WP:3RR. He has made similar edits to Molecule. All his edits are making the point that quantum chemistry is a branch of physics. --Bduke (Discussion) 08:29, 29 October 2012 (UTC)

Perhaps it is a branch of both physics and chemistry.--193.231.19.53 (talk) 11:09, 27 November 2014 (UTC)

Bohmian quantum chemistry[edit]

Some details about quantum chemistry based on Bohmian mechanics should be inserted in article.--5.15.14.104 (talk) 08:51, 25 November 2014 (UTC)

Do you have any reliable sources? --Bduke (Discussion) 09:26, 25 November 2014 (UTC)
A Google search for Bohmian quantum chemistry gives some results, like one from Eur. Phys. J. D (2014) 68: 286 which is also on arxiv and says: Fifteen years ago, the quantum chemistry community began to study the practical usefulness of Bohmian mechanics.--5.15.15.105 (talk) 21:25, 25 November 2014 (UTC)
I will take a look at that reference, but I think it is going to need more than that. I suppose I am part of the quantum chemistry community in a sense, but I do not think I have ever come across anything on Bohmian quantum chemistry, although I could be forgetting it in my old age of course. --Bduke (Discussion) 21:40, 25 November 2014 (UTC)