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

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

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