From owner-chemistry@ccl.net Wed Sep 3 07:50:01 2014 From: "Igors Mihailovs igors.mihailovs0-.-gmail.com" To: CCL Subject: CCL:G: about electron affinity Message-Id: <-50472-140903053055-7353-n0BLtUmqxnVGfUWzOjrO4g(0)server.ccl.net> X-Original-From: Igors Mihailovs Content-Type: multipart/alternative; boundary=047d7b10cacfefe9c4050225e30c Date: Wed, 3 Sep 2014 12:30:24 +0300 MIME-Version: 1.0 Sent to CCL by: Igors Mihailovs [igors.mihailovs0.:.gmail.com] --047d7b10cacfefe9c4050225e30c Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Also, it may be useful to note here that the electron affinity is usually negative for either rather small aromatic molecules and those containing electron-donating groups (sp2-N, too, in this case, because it has lone pair), whereas for aromatics with many fused rings and those having electron accepting groups usually have positive EAs. The experimental results also may give controversial suggestions. For example, naphthalene has EA of =E2=80=930.20 eV, a value from ETS experimen= t, according to [D. M. A. Vera and A. B. Pierini, Phys. Chem. Chem. Phys., 2004, 6, 2899=E2=80=932903.], cited in the second paper suggested by Mr. Co= ok; but in [O. Dolgounitcheva,V. G. Zakrzewski and J. V. Ortiz, J. Phys. Chem. A 1997 101 (45), 8554-8564] value for naphthalene from photoelectron spectra is +0.14 eV. With best regards, Igors Mihailovs Institute of Solid State Physics, University of Latvia 2014-09-03 4:47 GMT+03:00 Ronald Cook cookrl/atda.com < owner-chemistry[-]ccl.net>: > There are four papers that address positive and negative electron > affinities and the latter two address the computation of negative electro= n > affinities > > 1) Tozer, David J., and Frank De Proft. "Computation of the hardness and > the problem of negative electron affinities in density functional theory.= " *The > Journal of Physical Chemistry A* 109.39 (2005): 8923-8929. > > 2)De Proft, Frank, et al. "Calculation of negative electron affinity and > aqueous anion hardness using Kohn=E2=80=93Sham HOMO and LUMO energies." *= Faraday > discussions* 135 (2007): 151-159. > > 3)Puiatti, Marcelo, D. Mariano A. Vera, and Adriana B. Pierini. "Species > with negative electron affinity and standard DFT methods. Finding the > valence anions." *Physical Chemistry Chemical Physics* 10.10 (2008): > 1394-1399. > > 4)Puiatti, Marcelo, D. Mariano A. Vera, and Adriana B. Pierini. "In searc= h > for an optimal methodology to calculate the valence electron affinities o= f > temporary anions." *Physical Chemistry Chemical Physics* 11.40 (2009): > 9013-9024. > > Ronald Cook > Principal Scientist > TDA Research, Inc. > > > On Tue, Sep 2, 2014 at 11:26 AM, Acioli, Paulo p-acioli|,|neiu.edu < > owner-chemistry]_[ccl.net> wrote: > >> You will always get negative electron binding energy at the HF level. >> Negative ions require correlation. Once you co to a post-HF method, if y= our >> molecule can bind an electron, you should be able to obtain a positive >> electron affinity. >> >> Paulo Acioli, Chair Earth Science and Physics >> >> Associate Professor of Physics >> >> Department of Physics and Astronomy >> >> Northeastern Illinois University >> >> 5500 North St. Louis Avenue, Chicago, IL 60625 >> >> Phone: (773) 442-4733 >> >> p-acioli]^[neiu.edu >> >> >> *http://www.neiu.edu/academics/college-of-arts-and-sciences/departments/= physics >> * >> >> >> >> On Tue, Sep 2, 2014 at 11:15 AM, Pierre Archirel pierre.archirel++ >> u-psud.fr wrote: >> >>> >>> Sent to CCL by: "Pierre Archirel" [pierre.archirel~~u-psud.fr] >>> Dear colleagues, >>> I have a closed shell molecule (rather large: 12 first row atoms) and I >>> want to know if this molecule can bind an electron. >>> DFT tells me "yes" with positive values of the electron affinity, in th= e >>> range 0.5-1.0 eV according to the functional. I suspect that these valu= es >>> are false, or at least largely overestimated. >>> I now turn to ab initio methods, but I first see that at the HF level >>> the electron is not bound and the SOMO built of the most diffuse gaussi= ans >>> of the basis. >>> The CCSD(T) and SAC-CI methods (which are affordable in my case) give a >>> negative electron affinity... but are these methods reliable? These met= hods >>> use the HF orbitals, can they bind an electron if it is not bound at th= e HF >>> level? >>> Or shall I use CAS methods (very expansive in my case) which optimize >>> orbitals at the CI level? Is it obligatory in this case? >>> Many thanks in advance, >>> Pierre Archirel >>> LCP, Universite Paris-Sud, Orsay, France >>> >>> >>> >>> -=3D This is automatically added to each message by the mailing script = =3D- >>> E-mail to subscribers: CHEMISTRY]^[ccl.net or use:>>> >>> E-mail to administrators: CHEMISTRY-REQUEST]^[ccl.net or use>>> >>> >>> >> > --047d7b10cacfefe9c4050225e30c Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Also, it may be useful to note here that the electron affi= nity is usually negative for either rather small aromatic molecules and tho= se containing electron-donating groups (sp2-N, too, in this case, because i= t has lone pair), whereas for aromatics with many fused rings and those hav= ing electron accepting groups usually have positive EAs.
The experimental results also may give controversial suggestions. For examp= le, naphthalene has EA of =E2=80=930.20 eV, a value from ETS experiment, ac= cording to [D. M. A. Vera and A. B. Pierini, Phys. Chem. Chem. Phys., 2004,= 6, 2899=E2=80=932903.], cited in the second paper suggested by Mr. Cook; b= ut in [O. Dolgounitcheva,V. G. Zakrzewski and J. V. Ortiz,
J. Phys. Chem. A 1997 101 (45), 8554-8564] value for naphthalene from = photoelectron spectra is +0.14 eV.

With best regards,
Igors Mihailovs
Institute of So= lid State Physics,
University of Latvia



2014-09-03 4:47 GMT+03:00 Ronald Cook co= okrl/atda.com <owner-chemistry[-]ccl.n= et>:
There are four papers that address positi= ve and negative electron affinities and the latter two address the computat= ion of negative electron affinities

1) Tozer, David J., and=20 Frank De Proft. "Computation of the hardness and the problem of negati= ve electron affinities in density functional theory." The Journal of = Physical Chemistry A 109.39 (2005): 8923-8929.

2)De Proft, Frank= , et al.=20 "Calculation of negative electron affinity and aqueous anion hardness= =20 using Kohn=E2=80=93Sham HOMO and LUMO energies." Faraday discussion= s 135 (2007): 151-159.

3)Puiatti, Marcelo, D.=20 Mariano A. Vera, and Adriana B. Pierini. "Species with negative electr= on affinity and standard DFT methods. Finding the valence anions." Ph= ysical Chemistry Chemical Physics 10.10 (2008): 1394-1399.

4)Pui= atti, Marcelo, D.=20 Mariano A. Vera, and Adriana B. Pierini. "In search for an optimal=20 methodology to calculate the valence electron affinities of temporary=20 anions." Physical Chemistry Chemical Physics 11.40 (2009): 9013= -9024.

Ronald Cook
Principal Scientist
TDA Research, Inc.


On Tue, Sep 2, 2014 at 11:26 AM, Aciol= i, Paulo p-acioli|,|neiu.edu<= /a> <owner-chemistry]_[ccl.net> wrote:
You will always get negativ= e electron binding energy at the HF level. Negative ions require correlatio= n. Once you co to a post-HF method, if your molecule can bind an electron, = you should be able to obtain a positive electron affinity.=C2=A0

Paulo Acioli, Chair Earth Science and Physics=C2=A0

Associate Professor of Physics=C2=A0

Departm= ent of Physics and Astronomy

Northeastern Illinois University

= 5500 North St. Louis Avenue, Chicago, IL 60625

Phone: (773) 442-4733<= /a>

p-acioli]^[neiu.edu


http://www.neiu.edu/academics/college-of-arts-and-sciences/departm= ents/physics

3D""



On Tue, Sep 2, 2014= at 11:15 AM, Pierre Archirel pierre.archirel++u-psud.fr <owner-chemistry]^[ccl.net&= gt; wrote:

Sent to CCL by: "Pierre=C2=A0 Archirel" [pierre.archirel~~u-psud.fr]
Dear colleagues,
I have a closed shell molecule (rather large: 12 first row atoms) and I wan= t to know if this molecule can bind an electron.
DFT tells me "yes" with positive values of the electron affinity,= in the range 0.5-1.0 eV according to the functional. I suspect that these = values are false, or at least largely overestimated.
I now turn to ab initio methods, but I first see that at the HF level the e= lectron is not bound and the SOMO built of the most diffuse gaussians of th= e basis.
The CCSD(T) and SAC-CI methods (which are affordable in my case) give a neg= ative electron affinity... but are these methods reliable? These methods us= e the HF orbitals, can they bind an electron if it is not bound at the HF l= evel?
Or shall I use CAS methods (very expansive in my case) which optimize orbit= als at the CI level? Is it obligatory in this case?
Many thanks in advance,
Pierre Archirel
LCP, Universite Paris-Sud, Orsay, France



-=3D This is automatically added to each message by the mailing script =3D-=
E-mail to subscribers: CHEMISTRY]^[ccl.net or use:
=C2=A0 =C2=A0 =C2=A0 http://www.ccl.net/cgi-bin/ccl/send_ccl_message=

E-mail to administrators: CHEMISTRY-REQUEST]^[ccl.net or use

=C2=A0 =C2=A0 =C2=A0 http://www.ccl.net/cgi-bin/ccl/send_ccl_message=

Subscribe/Unsubscribe:
=C2=A0 =C2=A0 =C2=A0 http://www.ccl.net/chemistry/sub_unsub.shtml

Before posting, check wait time at: http://www.ccl.net

Job: http://www.ccl.n= et/jobs
Conferences: http://server.ccl.net/chemistry/announcements/co= nferences/

Search Messages: http://www.ccl.net/chemistry/searchccl/index.shtml



--047d7b10cacfefe9c4050225e30c--