From owner-chemistry@ccl.net Thu Jul 2 01:54:00 2020 From: "E H non ricouhenon*gmail.com" To: CCL Subject: CCL: IGMPlot program Message-Id: <-54132-200701111232-4965-8NTTzATiSW/akUrf4lgNMA|*|server.ccl.net> X-Original-From: "E H non" Date: Wed, 1 Jul 2020 11:12:31 -0400 Sent to CCL by: "E H non" [ricouhenon,+,gmail.com] Dear Colleagues, We are pleased to announce the new IGMPlot release version 2.6.7 - June 2020, which is available for download at http://igmplot.univ-reims.fr . Apologies for any possible cross-posting. This program identifies and quantifies molecular interactions over a broad range: from non-covalent to covalent bonding. IGMPlot relies on an electron-density based descriptor working with either pro-molecular density or with an electron density obtained > from wave-function calculations. New Features: ------------------ - IBSI index: an Intrinsic Bond Strength Index (does not belong to the conventional class of bond orders like Mulliken or Mayer, or the Delocalization Index) - BAF index: a Bond Asymmetry Factor - WFX file format is now supported - Development of a scoring function from pro-molecular electron density (possibility to probe non-covalent inter-fragment interactions or weak intra-molecular interactions) - Quantifying intra-molecular pi-pi stacking at the QM level of theory - Accelerated performances Kind regards. Eric Hnon Prof. Eric Henon ICMR (Institut de Chimie Molculaire de Reims) Groupe Biomolecules : Synthese et Mecanismes d'Action UMR CNRS 7312 Universit de Reims Champagne-Ardenne 51687 Reims Cedex 2 BP 39 FRANCE eric.henon/./univ-reims.fr From owner-chemistry@ccl.net Thu Jul 2 11:13:00 2020 From: "Muhammed Buyuktemiz mbtemiz3]~[gmail.com" To: CCL Subject: CCL: Reaction of an anion with a closed shell molecule with CASSCF Message-Id: <-54133-200702041914-4643-8X2Ue23Q22cm3IgdFUssxg^server.ccl.net> X-Original-From: "Muhammed Buyuktemiz" Date: Thu, 2 Jul 2020 04:19:10 -0400 Sent to CCL by: "Muhammed Buyuktemiz" [mbtemiz3^gmail.com] Dear CCLers, I am trying to investigate the electron transfer processes for a reaction between an anion and a closed shell molecule. As a specific example, you may consider the reaction between hydroxide and acyl chloride. Initially, I am placing two species at 10 A apart from each other and presume that the two are infinitely separated, i.e the ion and the acyl chloride don't `feel` each other. Later on I am carrying relaxed geometry optimizations by keeping inter-molecular distance r constant while r is decreased in subsequent calculations. However, I am having difficulty in understanding/interpreting the wavefunction for the infinitely separated species. At 10 A, CASSCF optimized wavefunction* shows two major configurations each with 0.60 coefficients. The first configuration shows what I would normally expect, an OH(-) ion and a closed shell Acyl Chloride electronic structure. The problem I have is related to the second configuration; This configuration shows that an electron transfer takes place at 10 A and the electron is located on one of the antibonding orbitals of the acyl chloride, yielding OH(0) + Acyl Chloride(-) type of electronic structure. I assume this is not chemically correct (since the two are infinitely separated) and doesn't allow me to investigate the perturbations induced when OH- approaches to Acyl Chloride**. But most importantly, since Acyl Chloride now has an extra electron located on the antibonding orbital, C- Cl bond breaks up in the geometry optimization calculations.*** My initial thought on the problem was that this might be an unbalanced active space issue but various combinations also led to the same outcome. I now realize this may not surprising due to the variational nature of the calculation; OH(0) + Acyl Chloride(-) configuration is as important/stable as the OH(-) + Acyl Chloride configuration. However this sentiment alone does not fix the issue and I am stuck. Is there any way to work around this issue that will allow me to investigate what `happens` to orbitals on the OH- approach? Any suggestions are greatly appreciated. Thank you *: rest of the coefficients are smaller than 0.1. **: this problem also persists for smaller/larger intermolecular distances and choosing an arbitrary 10 A is not a problem. ***: OH(-) -- Acyl Chloride distance is kept at 10 A. From owner-chemistry@ccl.net Thu Jul 2 15:19:01 2020 From: "Alan Shusterman alan(_)reed.edu" To: CCL Subject: CCL: Reaction of an anion with a closed shell molecule with CASSCF Message-Id: <-54134-200702143441-6283-bDNXHchLbTzCaChYSw15RA++server.ccl.net> X-Original-From: Alan Shusterman Content-Type: multipart/alternative; boundary="000000000000e8895205a979a8c2" Date: Thu, 2 Jul 2020 11:34:22 -0700 MIME-Version: 1.0 Sent to CCL by: Alan Shusterman [alan..reed.edu] --000000000000e8895205a979a8c2 Content-Type: text/plain; charset="UTF-8" Dear Muhammed, Unfortunately, I can't shed any light on the technical aspects of the CASSCF calculation, but *qualitatively*, what you describe looks very much like the "curve crossing model" of chemical reactivity that has been used by Shaik and Pross and others. If you are looking for qualitative insights, I would search "curve crossing model". Good luck with your calculations. Alan On Thu, Jul 2, 2020 at 10:01 AM Muhammed Buyuktemiz mbtemiz3]~[gmail.com < owner-chemistry###ccl.net> wrote: > > Sent to CCL by: "Muhammed Buyuktemiz" [mbtemiz3^gmail.com] > Dear CCLers, > > I am trying to investigate the electron transfer processes for a reaction > between an anion and a closed shell molecule. As a specific example, you > may consider the reaction between hydroxide and acyl chloride. > > Initially, I am placing two species at 10 A apart from each other and > presume that the two are infinitely separated, i.e the ion and the acyl > chloride don't `feel` each other. Later on I am carrying relaxed geometry > optimizations by keeping inter-molecular distance r constant while r is > decreased in subsequent calculations. > However, I am having difficulty in understanding/interpreting the > wavefunction for the infinitely separated species. At 10 A, CASSCF > optimized wavefunction* shows two major configurations each with 0.60 > coefficients. The first configuration shows what I would normally expect, > an OH(-) ion and a closed shell Acyl Chloride electronic structure. The > problem I have is related to the second configuration; This configuration > shows that an electron transfer takes place at 10 A and the electron is > located on one of the antibonding orbitals of the acyl chloride, yielding > OH(0) + Acyl Chloride(-) type of electronic structure. > > I assume this is not chemically correct (since the two are infinitely > separated) and doesn't allow me to investigate the perturbations induced > when OH- approaches to Acyl Chloride**. But most importantly, since Acyl > Chloride now has an extra electron located on the antibonding orbital, C- > Cl bond breaks up in the geometry optimization calculations.*** > > My initial thought on the problem was that this might be an unbalanced > active space issue but various combinations also led to the same outcome. > I now realize this may not surprising due to the variational nature of > the calculation; OH(0) + Acyl Chloride(-) configuration is as > important/stable as the OH(-) + Acyl Chloride configuration. However this > sentiment alone does not fix the issue and I am stuck. > > Is there any way to work around this issue that will allow me to > investigate what `happens` to orbitals on the OH- approach? > > Any suggestions are greatly appreciated. Thank you > > > *: rest of the coefficients are smaller than 0.1. > **: this problem also persists for smaller/larger intermolecular > distances and choosing an arbitrary 10 A is not a problem. > ***: OH(-) -- Acyl Chloride distance is kept at 10 A.> > > -- Alan Shusterman Chemistry Department Reed College 3203 SE Woodstock Blvd Portland, OR 97202-8199 503-517-7699 http://blogs.reed.edu/alan/ "Patience, persistence, and a sense of humor." Dave Barrett (1956-2017, Reed College '77) --000000000000e8895205a979a8c2 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Dear Muhammed,

Unfortunately= , I can't shed any light on the technical aspects of the CASSCF calcula= tion, but qualitatively, what you describe looks very much like the = "curve crossing model" of chemical reactivity that has been used = by Shaik and Pross and others. If you are looking for qualitative insights,= I would search "curve crossing model". Good luck with your calcu= lations.

Alan

On Thu, Jul 2, 2020 at 10:0= 1 AM Muhammed Buyuktemiz mbtemiz3]~[gmail.com<= /a> <owner-chemistry###ccl.net<= /a>> wrote:
<= br> Sent to CCL by: "Muhammed=C2=A0 Buyuktemiz" [mbtemiz3^gmail.com]
Dear CCLers,

I am trying to investigate the electron transfer processes for a reaction <= br> between an anion and a closed shell molecule. As a specific example, you may consider the reaction between hydroxide and acyl chloride.

Initially, I am placing two species at 10 A apart from each other and
presume that the two are infinitely separated, i.e the ion and the acyl chloride don't `feel` each other. Later on I am carrying relaxed geomet= ry
optimizations by keeping inter-molecular distance r constant while r is decreased in subsequent calculations.
However, I am having difficulty in understanding/interpreting the
wavefunction for the infinitely separated species. At 10 A, CASSCF
optimized wavefunction* shows two major configurations each with 0.60
coefficients. The first configuration shows what I would normally expect, <= br> an OH(-) ion and a closed shell Acyl Chloride electronic structure. The problem I have is related to the second configuration; This configuration <= br> shows that an electron transfer takes place at 10 A and the electron is located on one of the antibonding orbitals of the acyl chloride, yielding <= br> OH(0) + Acyl Chloride(-) type of electronic structure.

I assume this is not chemically correct (since the two are infinitely
separated) and doesn't allow me to investigate the perturbations induce= d
when OH- approaches to Acyl Chloride**. But most importantly, since Acyl Chloride now has an extra electron located on the antibonding orbital, C- Cl bond breaks up in the geometry optimization calculations.***

My initial thought on the problem was that this might be an unbalanced
active space issue but various combinations also led to the same outcome. <= br> I now realize this may not surprising due to the variational nature of
the calculation; OH(0) + Acyl Chloride(-) configuration is as
important/stable as the OH(-) + Acyl Chloride configuration. However this <= br> sentiment alone does not fix the issue and I am stuck.

Is there any way to work around this issue that will allow me to
investigate what `happens` to orbitals on the OH- approach?

Any suggestions are greatly appreciated. Thank you


*: rest of the coefficients are smaller than 0.1.
**: this problem also persists for smaller/larger intermolecular
distances and choosing an arbitrary 10 A is not a problem.
***: OH(-) -- Acyl Chloride distance is kept at 10 A.



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--
Alan Shusterman
Chemistry Department
Reed College
3203 SE Woodst= ock Blvd
Portland, OR 97202-8199
503-517-7699
http://blogs.reed.edu/alan/
&q= uot;Patience, persistence, and a sense of humor." Dave Barrett (1956-2= 017, Reed College '77)
--000000000000e8895205a979a8c2--