From owner-chemistry@ccl.net Fri Oct 29 20:21:01 2010 From: "Eric Scerri scerri.:.chem.ucla.edu" To: CCL Subject: CCL: question on Born-Oppenheimer approx. Message-Id: <-43037-101029202000-2771-bFQrZCGGMdMn51hbM5GiaQ{=}server.ccl.net> X-Original-From: Eric Scerri Content-Type: multipart/alternative; boundary=Apple-Mail-27-853188524 Date: Fri, 29 Oct 2010 17:20:33 -0700 Mime-Version: 1.0 (Apple Message framework v936) Sent to CCL by: Eric Scerri [scerri*o*chem.ucla.edu] --Apple-Mail-27-853188524 Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes Content-Transfer-Encoding: 7bit Dear CCL'ers For many years now a few theoretical chemists (Primas, Woolley, Sutcliffe) have claimed that there is something significant going on in connection with the Born-Oppenheimer approximation. They claim that applying the approximation amounts to writing the structure of a molecule in 'by hand' rather than the structure being inherent in the quantum formalism. They cite examples such as C2H5OH and CH3OCH3 which share the same Hamiltonian and conclude that structure cannot therefore be deduced > from QM in an ab initio fashion. Some philosophers of chemistry have taken this a good deal further as a sign that chemistry (molecular structure) cannot be strictly reduced to quantum mechanics. Some even claim that there is 'emergence' taking place. Most chemists I have discussed this issue with claim that these philosophers and even the theoretical chemists mentioned above are reaching incorrect conclusions. Most chemists claim that structure does really exist as a matter of fact and that we could in principle solve the Schrodinger equation without fixing the position of the nuclei by solving the equation for every conceivable arrangement and would thereby recover the inherent structure. I would be interested in comments and have a follow-up question if there is any interest in this topic. all the best, eric scerri Eric Scerri, The Periodic Table, Its Story and Its Significance, Oxford University Press, 2007 http://www.oup.com/us/catalog/general/subject/Chemistry/?view=usa&ci=9780195305739 --Apple-Mail-27-853188524 Content-Type: text/html; charset=US-ASCII Content-Transfer-Encoding: quoted-printable

Dear = CCL'ers

For many years now a few theoretical = chemists (Primas, Woolley, Sutcliffe) have claimed that there is = something significant going on in connection with the Born-Oppenheimer = approximation.  

They claim that applying = the approximation amounts to writing the structure of a molecule in 'by = hand' rather than the structure being inherent in the quantum formalism. =  

They cite examples such as C2H5OH and = CH3OCH3 which share the same Hamiltonian and conclude that structure = cannot therefore be deduced from QM in an ab initio fashion. =  

Some philosophers of chemistry have = taken this a good deal further as a sign that chemistry (molecular = structure) cannot be strictly reduced to quantum mechanics.  Some = even claim that there is 'emergence' taking place. =  

Most chemists I have discussed this = issue with claim that these philosophers and even the theoretical = chemists mentioned above are reaching incorrect conclusions.  Most = chemists claim that structure does really exist as a matter of fact and = that we could in principle solve the Schrodinger equation without fixing = the position of the nuclei by solving the equation for every conceivable = arrangement and would thereby recover the inherent structure. =  

I would be interested in comments and = have a follow-up question if there is any interest in this topic.   =    

all the best,
eric = scerri



Eric Scerri, The Periodic Table, Its Story and Its Significance, = Oxford University Press, 2007

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