From owner-chemistry@ccl.net Wed Sep 29 00:37:00 2021 From: "Christoph Riplinger christoph.riplinger .. gmail.com" To: CCL Subject: CCL: How to find barrier less transition state Message-Id: <-54462-210928143903-24830-NKtIkJ/vAJf8/JPlUAeGcQ*server.ccl.net> X-Original-From: Christoph Riplinger Content-Language: en-US Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=utf-8 Date: Tue, 28 Sep 2021 20:38:52 +0200 MIME-Version: 1.0 Sent to CCL by: Christoph Riplinger [christoph.riplinger_+_gmail.com] With ORCA you can use an NEB (or NEB-TS) calculation starting from the reactant and product structures in order to obtain the minimum energy path. If the reaction is barrierless, that path will be downhill. On 28.09.21 14:30, Sumangla Arora arorasumangla%gmail.com wrote: > Sent to CCL by: "Sumangla Arora" [arorasumangla*_*gmail.com] > Dear All, > I am having difficulty getting a transition state between two intermediates. > When I run a guess structure, I got one imaginary mode. However, when I put > this structure for OPTTS in orca, this structure is immediately converting into > the product. To me, this transition state is barrier less. > How can I find this transition state? or > If suppose there is no transition state then how can I prove that?> > From owner-chemistry@ccl.net Wed Sep 29 01:11:01 2021 From: "quapp a mathematik.uni-leipzig.de" To: CCL Subject: CCL: How to find barrier less transition state Message-Id: <-54463-210929010628-14116-nahKVnt8BIuUngbHtCQGCQ*server.ccl.net> X-Original-From: quapp---mathematik.uni-leipzig.de Content-Disposition: inline Content-Type: text/plain; charset=utf-8; format=flowed; DelSp=Yes Date: Wed, 29 Sep 2021 07:06:16 +0200 MIME-Version: 1.0 Sent to CCL by: quapp~~mathematik.uni-leipzig.de Dear Sumangla, there are indeed barrier-less transitions, but I think You mean another problem? Nevertheless, see: W.Quapp, E.Kraka, D.Cremer: Journal of Physical Chemistry, 111, Issue 44 (2007) 11287-11293, "Finding the transition state of quasi barrier-less reactions by a growing string method for Newton trajectories: applications to the dissociation of Methylenecyclopropene and Cyclopropane" and Hyun Joo, E.Kraka, W.Quapp, D.Cremer: Molecular Physics, 105, Issue 19-22 (2007) 2697-2717, "The Mechanism of a Barrierless Reaction: Hidden Transition State and Hidden Intermediates in the Reaction of Methylene with Ethene" Regards Wolfgang Quapp ----- Nachricht von "Sumangla Arora arorasumangla%gmail.com" --------- Datum: Tue, 28 Sep 2021 08:30:15 -0400 Von: "Sumangla Arora arorasumangla%gmail.com" Antwort an: CCL Subscribers Betreff: [Extern] CCL: How to find barrier less transition state An: "Quapp, Wolfgang " > Sent to CCL by: "Sumangla Arora" [arorasumangla*_*gmail.com] > Dear All, > I am having difficulty getting a transition state between two intermediates. > When I run a guess structure, I got one imaginary mode. However, when I put > this structure for OPTTS in orca, this structure is immediately > converting into > the product. To me, this transition state is barrier less. > How can I find this transition state? or > If suppose there is no transition state then how can I prove that? > > > From owner-chemistry@ccl.net Wed Sep 29 08:14:00 2021 From: "Yavuz Dede dede\a/gazi.edu.tr" To: CCL Subject: CCL: How to find barrier less transition state Message-Id: <-54464-210929081257-14665-vx5eiuBagREuAzxi/7Zhcg^^server.ccl.net> X-Original-From: Yavuz Dede Content-Language: en-US Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=utf-8; format=flowed Date: Wed, 29 Sep 2021 15:12:45 +0300 MIME-Version: 1.0 Sent to CCL by: Yavuz Dede [dede%%gazi.edu.tr] Sumangla, You might want  to have a look at variational TS theory if you have an association/dissociation rxn. The book on unimolecular rxns by Wendell Forst can help. Best, Yavuz On 09/29/21 08:06, quapp a mathematik.uni-leipzig.de wrote: > > Sent to CCL by: quapp~~mathematik.uni-leipzig.de > > Dear Sumangla, > > there are indeed barrier-less transitions, but I think You mean > another problem? > Nevertheless, see: > >  W.Quapp, E.Kraka, D.Cremer: Journal of Physical Chemistry, 111, Issue > 44 (2007) 11287-11293, > "Finding the transition state of quasi barrier-less reactions by a > growing string method for >  Newton trajectories: applications to the dissociation of > Methylenecyclopropene and Cyclopropane" > and > Hyun Joo, E.Kraka, W.Quapp, D.Cremer: Molecular Physics, 105, Issue > 19-22 (2007) 2697-2717, > "The Mechanism of a Barrierless Reaction: Hidden Transition State and > Hidden Intermediates >  in the Reaction of Methylene with Ethene" > > Regards > Wolfgang Quapp > > > > ----- Nachricht von "Sumangla Arora arorasumangla%gmail.com" > --------- >      Datum: Tue, 28 Sep 2021 08:30:15 -0400 >        Von: "Sumangla Arora arorasumangla%gmail.com" > > Antwort an: CCL Subscribers >    Betreff: [Extern] CCL: How to find barrier less transition state >         An: "Quapp, Wolfgang " > > >> Sent to CCL by: "Sumangla  Arora" [arorasumangla*_*gmail.com] >> Dear All, >> I am having difficulty getting a transition state between two >> intermediates. >> When I run a guess structure, I got one imaginary mode. However, when >> I put >> this structure for OPTTS in orca, this structure is immediately >> converting into >> the product. To me, this transition state is barrier less. >> How can I find this transition state? or >> If suppose there is no transition state then how can I prove that?>     >     http://www.ccl.net/chemistry/sub_unsub.shtml> > Job: http://www.ccl.net/jobsConferences: > http://server.ccl.net/chemistry/announcements/conferences/>     > > > -- ~~~~~~~~~~~~~~~~~ Doç. Dr. Yavuz Dede G.Ü. Fen Fakültesi, Kimya Bölümü L-128 06500 Ankara Tel: +90 312-202-1386 Faks: +90 312-212-2279 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Yavuz Dede, Ph.D. Assoc. Prof. of Theoretical/Computational Chemistry Gazi University, Faculty of Science Department of Chemistry 06500 Ankara TURKEY http://w3.gazi.edu.tr/~dede/ydd.html ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~