From owner-chemistry@ccl.net Wed Oct 3 21:12:01 2012 From: "Amy Austin amy_jean_austin!^!yahoo.com" To: CCL Subject: CCL: Resonance energy Message-Id: <-47709-121003191054-20903-UGblJhHCRhLlm/aY0tUb9g+/-server.ccl.net> X-Original-From: Amy Austin Content-Type: multipart/alternative; boundary="1073417382-1635669292-1349305847=:68944" Date: Wed, 3 Oct 2012 16:10:47 -0700 (PDT) MIME-Version: 1.0 Sent to CCL by: Amy Austin [amy_jean_austin.:.yahoo.com] --1073417382-1635669292-1349305847=:68944 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Hi Sergio,=0A=0AMaybe my thinking is too simplistic. It seems like you coul= d calculate the predicted value for the enthalpy of complete hydrogenation = of your system which would be N times (N=3D# double bonds) that of one doub= le bond). Then subtract the actual predicted value for the complete hydroge= nation (which will be less due to the resonance stabilization). That differ= ence should be the resonance energy of the system.=0A=0AOpinions to this te= chnique are welcome - Please reply privately.=0A=0AI don't recommend using = HF values for the resonance energy. I think you need to include instantaneo= us correlation at some level in order to have meaningful results. If you ne= ed to conserve on CPU time, I would recommend a DFT.=0A=0AHope this helps!= =0A=0AAmy=0A=0A=0A=0A=0A________________________________=0A From: Sergio Ma= nzetti sergio.manzetti^-^gmx.com =0ATo: "Austin, A= my J " =0ASent: Wednesday, October 3, 2= 012 11:10 AM=0ASubject: CCL: Resonance energy=0A =0A=0ADifficult indeed Rob= erto!=0A=0AIs there a way of mapping the resonance energy or conjugation pa= ttern straight from a SCF calculation?=0A=0A=0A=0A=0A=A0=0A----- Original M= essage -----=0A>From: Robert W. Gora robert.gora()pwr.wroc.pl=0A>Sent: 10/0= 3/12 04:40 PM=0A>To: Manzetti, Sergio =0A>Subject: CCL: Resonance energy=0A= >=0A>> Dear CCLrs, how can one extract the parameters of "resonance energy"= =0A> (Randic, 2003) from a SCF calculation of a neutral ring system? One = cannot, in my opinion you need a vb code for that :) Have a look at Rashid = =0Aet al. J. Phys. Chem. A 116, 4778-4788 (2012) [DOI 10.1021/jp211105t] = =0ATry van Lenthe's from gamess(uk) or Cooper's SCVB from Molcas/Molpro. C= heers, =0ARobert -- =0ARobert W. G=F3ra, Theoretical Chemistry Group, ICHF= iT, WUT [http://zcht.info] =0A[http://www.researchgate.net/profile/Robert_G= ora] =0A[http://www.researcherid.com/rid/B-3919-2010] --1073417382-1635669292-1349305847=:68944 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
Hi Sergio,

May= be my thinking is too simplistic. It seems like you could calculate the pre= dicted value for the enthalpy of complete hydrogenation of your system whic= h would be N times (N=3D# double bonds) that of one double bond). Then subt= ract the actual predicted value for the complete hydrogenation (which will = be less due to the resonance stabilization). That difference should be the = resonance energy of the system.

Opinions to this technique are welco= me - Please reply privately.

I don't recommend using HF values for t= he resonance energy. I think you need to include instantaneous correlation = at some level in order to have meaningful results. If you need to conserve = on CPU time, I would recommend a DFT.

Hope this helps!

Amy


From: Sergio Manzetti sergio.manzett= i^-^gmx.com <owner-chemistry..ccl.net>
To: "Austin, Amy J " <amy_jean_austin..yaho= o.com>
Sent: Wedne= sday, October 3, 2012 11:10 AM
Su= bject: CCL: Resonance energy

=0A
Diff= icult indeed Roberto!
=0A
=0AIs there a way of mapping the resonanc= e energy or conjugation pattern straight from a SCF calculation?
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=0A=09
=0A=09=09----- Original Messa= ge -----
=0A=09
= =0A=09=09From: Robert W. Gora robert.gora()pwr.wroc.pl
=0A=09
=0A=09=09Sent: 10/03/12 04:40 PM
=0A=09 =0A=09=09To: Manzetti, Sergio =
=0A=09
=0A=09=09Subject: CCL: Res= onance energy
=0A=09
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=0A= =09=09=09
 =0A> Dear CCLrs, how can one extract the parameters of "resonance =
energy" =0A> (Randic, 2003) from a SCF calculation of a neutral ring sys=
tem? =0A=0AOne cannot, in my opinion you need a vb code for that :) Have a =
look at Rashid =0Aet al. J. Phys. Chem. A 116, 4778-4788 (2012) [DOI 10.102=
1/jp211105t] =0ATry van Lenthe's from gamess(uk) or Cooper's SCVB from Molc=
as/Molpro. =0A=0ACheers, =0ARobert =0A=0A-- =0ARobert W. G=F3ra, Theoretica=
l Chemistry Group, ICHFiT, WUT [http://zcht.info] =0A[http://www.researchga=
te.net/profile/Robert_Gora] =0A[http://www.researcherid.com/rid/B-3919-2010=
]
=0A=09=09
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