From owner-chemistry@ccl.net Tue Jan 7 04:25:00 2020
From: "Susi Lehtola susi.lehtola[*]helsinki.fi" <owner-chemistry * server.ccl.net>
To: CCL
Subject: CCL: The best method to calculate the ionization potential of organic mol.
Message-Id: <-53927-200107040834-22247-E7XaLeGb+TLQh8o5wKlelA * server.ccl.net>
X-Original-From: Susi Lehtola <susi.lehtola**helsinki.fi>
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Date: Tue, 7 Jan 2020 11:08:23 +0200
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Sent to CCL by: Susi Lehtola [susi.lehtola a helsinki.fi]
On 1/7/20 12:26 AM, Daniel Glossman-Mitnik dglossman _ gmail.com wrote:
> The Koopmans' theorem (note that it is Koopmans, not Koopman) does not
> (theoretically) hold within DFT and it has been always used as approximation.
> However, there is another theorem that it is valid within Generalized Kohn-Sham
> model (GKS) that validates the use of E(HOMO as -I. This does not hold for A and
> the LUMO, but it can be said that A is equal to -E(HOMO) of the anion. From a
> practical point of view, if the E(HOMO) of the anion is equal to the E(LUMO) of
> the neutral, then this counterpart of Koopmans' theorem will hold within DFT.
> Indeed this is an approximation, and its accuracy will be depending on the model
> chemistry chosen for your calculations. In our research group, we have been
> doing investigations to find the best model chemistry that satisfies this
> approximation and our published results show that the MN12SX/Def2TZVP/H20
> reproduce the values with great accuracy. Of course, there could be another
> combinations that could help (including tuned density functionals to get the
> desired Koopmans behavior) but most of the usually recommended density
> functionals are not useful in this regard.
Bartlett's "consistent DFT" should also be mentioned in this context; their QTP
functionals are obtained by enforcing correct excitation spectra. See dois
10.1016/j.cplett.2016.12.017 and 10.1063/1.5116338.
--
------------------------------------------------------------------
Mr. Susi Lehtola, PhD Junior Fellow, Adjunct Professor
susi.lehtola(a)alumni.helsinki.fi University of Helsinki
http://susilehtola.github.io/ Finland
------------------------------------------------------------------
Susi Lehtola, dosentti, FT tutkijatohtori
susi.lehtola(a)alumni.helsinki.fi Helsingin yliopisto
http://susilehtola.github.io/
------------------------------------------------------------------
From owner-chemistry@ccl.net Tue Jan 7 07:47:00 2020
From: "Robert Molt r.molt.chemical.physics{:}gmail.com" <owner-chemistry:-:server.ccl.net>
To: CCL
Subject: CCL: The best method to calculate the ionization potential of organic mol.
Message-Id: <-53928-200107074552-15090-Z+govhv+cFrGMa6Et5GKfg:-:server.ccl.net>
X-Original-From: Robert Molt <r.molt.chemical.physics * gmail.com>
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Sent to CCL by: Robert Molt [r.molt.chemical.physics!A!gmail.com]
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1.) Dr. Lehtola=E2=80=99s suggestion is correct. A distinction should be =
made when saying that =E2=80=9CKoopmans=E2=80=99s theorem does not hold =
for DFT.=E2=80=9D Whether or not =E2=80=9Cthe true=E2=80=9D DFT should =
have Koopmans=E2=80=99s theorem is a subject of some scholarly debate. =
Dr. Bartlett=E2=80=99s work is intended to be proof that a =
well-formulated DFT, with emphasis on enforcing physical constraints, =
can do this. This is meant to be in contrast to the zoo of highly =
parameterized KS-DFT functionals, which do badly poorly outside their =
parameterization range (the Minnesota functionals being an example which =
are stupendous at many, many things, then bizarrely terrible in certain =
circumstances outside the standard comp chem goals).
2.) None of this is intended to argue that Dr. Bartlett=E2=80=99s work =
is or is not the best you can do, accuracy -wise, right here right now.=20=
3.) The original question has a false dichotomy. The original question =
compared adiabatic vs. relaxed excitations (re-optimizing the structure =
of the cation or not) asking which was =E2=80=9Cmore accurate.=E2=80=9D =
This is wrong; my emphasis is intended for clarity, not to be =
pejorative. These correspond to two totally different experimental =
situations. If you are trying to model ionization energies, you should =
re-optimize the geometries iff you are comparing to experimental =
ionization energies where the system=E2=80=99s molecular geometry does =
have time to relax. The same is true that an adiabatic ionization energy =
must be compared to an adiabatic ionization experiment. Usually, people =
mean the adiabatic ionization energy if they do not qualify what they =
mean (but one should specify). It would be inconsistent to use relaxed =
structures to compute adiabatic ionization energies.
One could argue to do this anyway, on the grounds of judicious =
cancellation of error; I am ignorant, personally, of how errors cancel, =
assuming a systematic error exists in the first place. However, in so =
much as the goal of our field is to compute the right answer for the =
right reasons, it is inconsistent.
> On Jan 7, 2020, at 4:08 AM, Susi Lehtola susi.lehtola[*]helsinki.fi =
<owner-chemistry#ccl.net> wrote:
>=20
>=20
> Sent to CCL by: Susi Lehtola [susi.lehtola a helsinki.fi]
> On 1/7/20 12:26 AM, Daniel Glossman-Mitnik dglossman _ gmail.com =
wrote:
>> The Koopmans' theorem (note that it is Koopmans, not Koopman) does =
not (theoretically) hold within DFT and it has been always used as =
approximation. However, there is another theorem that it is valid within =
Generalized Kohn-Sham model (GKS) that validates the use of E(HOMO as =
-I. This does not hold for A and the LUMO, but it can be said that A is =
equal to -E(HOMO) of the anion. =46rom a practical point of view, if the =
E(HOMO) of the anion is equal to the E(LUMO) of the neutral, then this =
counterpart of Koopmans' theorem will hold within DFT. Indeed this is an =
approximation, and its accuracy will be depending on the model chemistry =
chosen for your calculations. In our research group, we have been doing =
investigations to find the best model chemistry that satisfies this =
approximation and our published results show that the =
MN12SX/Def2TZVP/H20 reproduce the values with great accuracy. Of course, =
there could be another combinations that could help (including tuned =
density functionals to get the desired Koopmans behavior) but most of =
the usually recommended density functionals are not useful in this =
regard.
>=20
> Bartlett's "consistent DFT" should also be mentioned in this context; =
their QTP functionals are obtained by enforcing correct excitation =
spectra. See dois 10.1016/j.cplett.2016.12.017 and 10.1063/1.5116338.
> --=20
> ------------------------------------------------------------------
> Mr. Susi Lehtola, PhD Junior Fellow, Adjunct Professor
> susi.lehtola() alumni.helsinki.fi University of Helsinki
> http://susilehtola.github.io/ Finland
> ------------------------------------------------------------------
> Susi Lehtola, dosentti, FT tutkijatohtori
> susi.lehtola() alumni.helsinki.fi Helsingin yliopisto
> http://susilehtola.github.io/
> ------------------------------------------------------------------
>=20
>=20
>=20
> -=3D This is automatically added to each message by the mailing script =
=3D-
> To recover the email address of the author of the message, please =
change>=20>=20>=20=>=20>=20Conferences: =
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>=20>=20>=20>=20
>=20
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charset=utf-8
<html><head><meta http-equiv=3D"Content-Type" content=3D"text/html; =
charset=3Dutf-8"></head><body style=3D"word-wrap: break-word; =
-webkit-nbsp-mode: space; line-break: after-white-space;" class=3D"">1.) =
Dr. Lehtola=E2=80=99s suggestion is correct. A distinction should be =
made when saying that =E2=80=9CKoopmans=E2=80=99s theorem does not hold =
for DFT.=E2=80=9D Whether or not =E2=80=9Cthe true=E2=80=9D DFT should =
have Koopmans=E2=80=99s theorem is a subject of some scholarly debate. =
Dr. Bartlett=E2=80=99s work is intended to be proof that a =
well-formulated DFT, with emphasis on enforcing physical constraints, =
can do this. This is meant to be in contrast to the zoo of highly =
parameterized KS-DFT functionals, which do badly poorly outside their =
parameterization range (the Minnesota functionals being an example which =
are stupendous at many, many things, then bizarrely terrible in certain =
circumstances outside the standard comp chem goals).<div class=3D""><br =
class=3D""></div><div class=3D"">2.) None of this is intended to argue =
that Dr. Bartlett=E2=80=99s work is or is not the best you can do, =
accuracy -wise, right here right now. </div><div class=3D""><br =
class=3D""></div><div class=3D"">3.) The original question has a false =
dichotomy. The original question compared adiabatic vs. relaxed =
excitations (re-optimizing the structure of the cation or not) asking =
which was =E2=80=9Cmore accurate.=E2=80=9D This is <b =
class=3D"">wrong</b>; my emphasis is intended for clarity, not to be =
pejorative. These correspond to two totally different experimental =
situations. If you are trying to model ionization energies, you should =
re-optimize the geometries iff you are comparing to experimental =
ionization energies where the system=E2=80=99s molecular geometry does =
have time to relax. The same is true that an adiabatic ionization energy =
must be compared to an adiabatic ionization experiment. Usually, people =
mean the adiabatic ionization energy if they do not qualify what they =
mean (but one should specify). It would be inconsistent to use relaxed =
structures to compute adiabatic ionization energies.</div><div =
class=3D""><br class=3D""></div><div class=3D"">One could argue to do =
this anyway, on the grounds of judicious cancellation of error; I am =
ignorant, personally, of how errors cancel, assuming a systematic error =
exists in the first place. However, in so much as the goal of our field =
is to compute the right answer for the right reasons, it is =
inconsistent.<br class=3D""><div><br class=3D""><blockquote type=3D"cite" =
class=3D""><div class=3D"">On Jan 7, 2020, at 4:08 AM, Susi Lehtola =
susi.lehtola[*]<a href=3D"http://helsinki.fi" class=3D"">helsinki.fi</a> =
<<a href=3D"mailto:owner-chemistry#ccl.net" =
class=3D"">owner-chemistry#ccl.net</a>> wrote:</div><br =
class=3D"Apple-interchange-newline"><div class=3D""><div class=3D""><br =
class=3D"">Sent to CCL by: Susi Lehtola [susi.lehtola a <a =
href=3D"http://helsinki.fi" class=3D"">helsinki.fi</a>]<br class=3D"">On =
1/7/20 12:26 AM, Daniel Glossman-Mitnik dglossman _ <a =
href=3D"http://gmail.com" class=3D"">gmail.com</a> wrote:<br =
class=3D""><blockquote type=3D"cite" class=3D"">The Koopmans' theorem =
(note that it is Koopmans, not Koopman) does not (theoretically) hold =
within DFT and it has been always used as approximation. However, there =
is another theorem that it is valid within Generalized Kohn-Sham model =
(GKS) that validates the use of E(HOMO as -I. This does not hold for A =
and the LUMO, but it can be said that A is equal to -E(HOMO) of the =
anion. =46rom a practical point of view, if the E(HOMO) of the anion is =
equal to the E(LUMO) of the neutral, then this counterpart of Koopmans' =
theorem will hold within DFT. Indeed this is an approximation, and its =
accuracy will be depending on the model chemistry chosen for your =
calculations. In our research group, we have been doing investigations =
to find the best model chemistry that satisfies this approximation and =
our published results show that the MN12SX/Def2TZVP/H20 reproduce the =
values with great accuracy. Of course, there could be another =
combinations that could help (including tuned density functionals to get =
the desired Koopmans behavior) but most of the usually recommended =
density functionals are not useful in this regard.<br =
class=3D""></blockquote><br class=3D"">Bartlett's "consistent DFT" =
should also be mentioned in this context; their QTP functionals are =
obtained by enforcing correct excitation spectra. See dois =
10.1016/j.cplett.2016.12.017 and 10.1063/1.5116338.<br class=3D"">-- <br =
class=3D"">---------------------------------------------------------------=
---<br class=3D"">Mr. Susi Lehtola, PhD =
Ju=
nior Fellow, Adjunct Professor<br class=3D"">susi.lehtola() <a =
href=3D"http://alumni.helsinki.fi" class=3D"">alumni.helsinki.fi</a> =
University of Helsinki<br class=3D""><a =
href=3D"http://susilehtola.github.io/" =
class=3D"">http://susilehtola.github.io/</a> =
Finland<br =
class=3D"">---------------------------------------------------------------=
---<br class=3D"">Susi Lehtola, dosentti, FT =
tutkijatohtori<br =
class=3D"">susi.lehtola() <a href=3D"http://alumni.helsinki.fi" =
class=3D"">alumni.helsinki.fi</a> Helsingin yliopisto<br =
class=3D""><a href=3D"http://susilehtola.github.io/" =
class=3D"">http://susilehtola.github.io/</a><br =
class=3D"">---------------------------------------------------------------=
---<br class=3D""><br class=3D""><br class=3D""><br class=3D"">-=3D This =
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From owner-chemistry@ccl.net Tue Jan 7 11:57:00 2020
From: "Igors Mihailovs igorsm,cfi.lu.lv" <owner-chemistry+*+server.ccl.net>
To: CCL
Subject: CCL: The best method to calculate the ionization potential of organic mol.
Message-Id: <-53929-200107111919-5116-dtafGbd9fEN3FABJhLrelg+*+server.ccl.net>
X-Original-From: Igors Mihailovs <igorsm=-=cfi.lu.lv>
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Sent to CCL by: Igors Mihailovs [igorsm**cfi.lu.lv]
This is a multi-part message in MIME format.
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Dear Dr. Molt,
I was somewhat sure that "adiabatic" ionization correspond to the
relaxed geometries. You probably intended to compare "vertical" and
"adiabatic" (or "relaxed-geometry"). Or am I wrong? As far as I know the
term "adiabatic" is because there is no further energy exchange with the
environment expected because the geometry has already been relaxed.
I also would like to add my bit to the discussion with the following points.
Adiabatic ionization energies and electron affinities are the quantities
needed to compare with experimental electrochemistry, for example (see
the Marcus equation), because the adiabatic difference is the driving
force, but the reorganization energies (difference between the adiabatic
and vertical quantities) are also involved because the transition is
vibrationally-assisted.
Also, unoccupied levels for the pure (non-hybrid) Kohn—Sham roughly
correspond to excitation energies rather than to electron affinities
(see, e.g., Baerends, E. J.; Gritsenko, O. V; van Meer, R. Phys. Chem.
Chem. Phys. 2013, 15 (39), 16408). This is lost when HF admixture is
introduced (as in hybrid functionals).
Also, I presume that optimally tuned range-separated hybrids are a more
or less viable alternative for the costly methods because, even if they
are tuned for every particular molecule, said generalized Koopmans'
theorem is the basis for tuning. I cannot find the article right now,
though, so I am not totally sure. For TD-DFT though, they are very good
(https://pubs.acs.org/doi/abs/10.1021/ct5000617).
With hope this is not rubbish,
Igors Mihailovs
On 1/7/20 2:45 PM, Robert Molt r.molt.chemical.physics{:}gmail.com wrote:
> 1.) Dr. Lehtola’s suggestion is correct. A distinction should be made
> when saying that “Koopmans’s theorem does not hold for DFT.” Whether
> or not “the true” DFT should have Koopmans’s theorem is a subject of
> some scholarly debate. Dr. Bartlett’s work is intended to be proof
> that a well-formulated DFT, with emphasis on enforcing physical
> constraints, can do this. This is meant to be in contrast to the zoo
> of highly parameterized KS-DFT functionals, which do badly poorly
> outside their parameterization range (the Minnesota functionals being
> an example which are stupendous at many, many things, then bizarrely
> terrible in certain circumstances outside the standard comp chem goals).
>
> 2.) None of this is intended to argue that Dr. Bartlett’s work is or
> is not the best you can do, accuracy -wise, right here right now.
>
> 3.) The original question has a false dichotomy. The original question
> compared adiabatic vs. relaxed excitations (re-optimizing the
> structure of the cation or not) asking which was “more accurate.” This
> is *wrong*; my emphasis is intended for clarity, not to be pejorative.
> These correspond to two totally different experimental situations. If
> you are trying to model ionization energies, you should re-optimize
> the geometries iff you are comparing to experimental ionization
> energies where the system’s molecular geometry does have time to
> relax. The same is true that an adiabatic ionization energy must be
> compared to an adiabatic ionization experiment. Usually, people mean
> the adiabatic ionization energy if they do not qualify what they mean
> (but one should specify). It would be inconsistent to use relaxed
> structures to compute adiabatic ionization energies.
>
> One could argue to do this anyway, on the grounds of judicious
> cancellation of error; I am ignorant, personally, of how errors
> cancel, assuming a systematic error exists in the first place.
> However, in so much as the goal of our field is to compute the right
> answer for the right reasons, it is inconsistent.
>
>> On Jan 7, 2020, at 4:08 AM, Susi Lehtola susi.lehtola[*]helsinki.fi
>> <http://helsinki.fi> <owner-chemistry/a\ccl.net
>> <mailto:owner-chemistry/a\ccl.net>> wrote:
>>
>>
>> Sent to CCL by: Susi Lehtola [susi.lehtola a helsinki.fi
>> <http://helsinki.fi>]
>> On 1/7/20 12:26 AM, Daniel Glossman-Mitnik dglossman _ gmail.com
>> <http://gmail.com> wrote:
>>> The Koopmans' theorem (note that it is Koopmans, not Koopman) does
>>> not (theoretically) hold within DFT and it has been always used as
>>> approximation. However, there is another theorem that it is valid
>>> within Generalized Kohn-Sham model (GKS) that validates the use of
>>> E(HOMO as -I. This does not hold for A and the LUMO, but it can be
>>> said that A is equal to -E(HOMO) of the anion. From a practical
>>> point of view, if the E(HOMO) of the anion is equal to the E(LUMO)
>>> of the neutral, then this counterpart of Koopmans' theorem will hold
>>> within DFT. Indeed this is an approximation, and its accuracy will
>>> be depending on the model chemistry chosen for your calculations. In
>>> our research group, we have been doing investigations to find the
>>> best model chemistry that satisfies this approximation and our
>>> published results show that the MN12SX/Def2TZVP/H20 reproduce the
>>> values with great accuracy. Of course, there could be another
>>> combinations that could help (including tuned density functionals to
>>> get the desired Koopmans behavior) but most of the usually
>>> recommended density functionals are not useful in this regard.
>>
>> Bartlett's "consistent DFT" should also be mentioned in this context;
>> their QTP functionals are obtained by enforcing correct excitation
>> spectra. See dois 10.1016/j.cplett.2016.12.017 and 10.1063/1.5116338.
>> --
>> ------------------------------------------------------------------
>> Mr. Susi Lehtola, PhD Junior Fellow, Adjunct Professor
>> susi.lehtola() alumni.helsinki.fi <http://alumni.helsinki.fi>
>> University of Helsinki
>> http://susilehtola.github.io/ Finland
>> ------------------------------------------------------------------
>> Susi Lehtola, dosentti, FT tutkijatohtori
>> susi.lehtola() alumni.helsinki.fi <http://alumni.helsinki.fi>
>> Helsingin yliopisto
>> http://susilehtola.github.io/
>> ------------------------------------------------------------------>> the strange characters on the top line to the /a\ sign. You can also>>
>> E-mail to subscribers: CHEMISTRY/a\ccl.net or use:
>> http://www.ccl.net/cgi-bin/ccl/send_ccl_message
>>
>> E-mail to administrators: CHEMISTRY-REQUEST/a\ccl.net or use
>> http://www.ccl.net/cgi-bin/ccl/send_ccl_messageConferences:
>> http://server.ccl.net/chemistry/announcements/conferences/>>
>> http://www.ccl.net/spammers.txt>>
>>
>
--
Ar cieņu,
Igors Mihailovs
Zinātniskais asistents
Organisko materiālu laboratorija
LU Cietvielu fizikas institūts
Yours faithfully,
Igors Mihailovs
Research assistant
Laboratory of Organic Materials
Institute of Solid State Physics, University of Latvia
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Dear Dr. Molt,<br>
<br>
I was somewhat sure that "adiabatic" ionization correspond to the
relaxed geometries. You probably intended to compare "vertical" and
"adiabatic" (or "relaxed-geometry"). Or am I wrong? As far as I know
the term "adiabatic" is because there is no further energy exchange
with the environment expected because the geometry has already been
relaxed.<br>
<br>
I also would like to add my bit to the discussion with the following
points.<br>
<br>
Adiabatic ionization energies and electron affinities are the
quantities needed to compare with experimental electrochemistry, for
example (see the Marcus equation), because the adiabatic difference
is the driving force, but the reorganization energies (difference
between the adiabatic and vertical quantities) are also involved
because the transition is vibrationally-assisted.<br>
<br>
Also, unoccupied levels for the pure (non-hybrid) Kohn—Sham roughly
correspond to excitation energies rather than to electron affinities
(see, e.g., Baerends, E. J.; Gritsenko, O. V; van Meer, R. Phys.
Chem. Chem. Phys. 2013, 15 (39), 16408). This is lost when HF
admixture is introduced (as in hybrid functionals).<br>
<br>
Also, I presume that optimally tuned range-separated hybrids are a
more or less viable alternative for the costly methods because, even
if they are tuned for every particular molecule, said generalized
Koopmans' theorem is the basis for tuning. I cannot find the article
right now, though, so I am not totally sure. For TD-DFT though, they
are very good (<a class="moz-txt-link-freetext" href="https://pubs.acs.org/doi/abs/10.1021/ct5000617">https://pubs.acs.org/doi/abs/10.1021/ct5000617</a>).<br>
<br>
With hope this is not rubbish,<br>
Igors Mihailovs<br>
<br>
<div class="moz-cite-prefix">On 1/7/20 2:45 PM, Robert Molt
r.molt.chemical.physics{:}gmail.com wrote:<br>
</div>
<blockquote type="cite"
cite="mid:-id%234fh-53928-200107074552-15090-xl4BbPhSnBsW0hta8Z4hWw * server.ccl.net">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
1.) Dr. Lehtola’s suggestion is correct. A distinction should be
made when saying that “Koopmans’s theorem does not hold for DFT.”
Whether or not “the true” DFT should have Koopmans’s theorem is a
subject of some scholarly debate. Dr. Bartlett’s work is intended
to be proof that a well-formulated DFT, with emphasis on enforcing
physical constraints, can do this. This is meant to be in contrast
to the zoo of highly parameterized KS-DFT functionals, which do
badly poorly outside their parameterization range (the Minnesota
functionals being an example which are stupendous at many, many
things, then bizarrely terrible in certain circumstances outside
the standard comp chem goals).
<div class=""><br class="">
</div>
<div class="">2.) None of this is intended to argue that Dr.
Bartlett’s work is or is not the best you can do, accuracy
-wise, right here right now. </div>
<div class=""><br class="">
</div>
<div class="">3.) The original question has a false dichotomy. The
original question compared adiabatic vs. relaxed excitations
(re-optimizing the structure of the cation or not) asking which
was “more accurate.” This is <b class="">wrong</b>; my emphasis
is intended for clarity, not to be pejorative. These correspond
to two totally different experimental situations. If you are
trying to model ionization energies, you should re-optimize the
geometries iff you are comparing to experimental ionization
energies where the system’s molecular geometry does have time to
relax. The same is true that an adiabatic ionization energy must
be compared to an adiabatic ionization experiment. Usually,
people mean the adiabatic ionization energy if they do not
qualify what they mean (but one should specify). It would be
inconsistent to use relaxed structures to compute adiabatic
ionization energies.</div>
<div class=""><br class="">
</div>
<div class="">One could argue to do this anyway, on the grounds of
judicious cancellation of error; I am ignorant, personally, of
how errors cancel, assuming a systematic error exists in the
first place. However, in so much as the goal of our field is to
compute the right answer for the right reasons, it is
inconsistent.<br class="">
<div><br class="">
<blockquote type="cite" class="">
<div class="">On Jan 7, 2020, at 4:08 AM, Susi Lehtola
susi.lehtola[*]<a href="http://helsinki.fi" class=""
moz-do-not-send="true">helsinki.fi</a> <<a
href="mailto:owner-chemistry/a\ccl.net" class=""
moz-do-not-send="true">owner-chemistry/a\ccl.net</a>>
wrote:</div>
<br class="Apple-interchange-newline">
<div class="">
<div class=""><br class="">
Sent to CCL by: Susi Lehtola [susi.lehtola a <a
href="http://helsinki.fi" class=""
moz-do-not-send="true">helsinki.fi</a>]<br class="">
On 1/7/20 12:26 AM, Daniel Glossman-Mitnik dglossman _ <a
href="http://gmail.com" class=""
moz-do-not-send="true">gmail.com</a> wrote:<br
class="">
<blockquote type="cite" class="">The Koopmans' theorem
(note that it is Koopmans, not Koopman) does not
(theoretically) hold within DFT and it has been always
used as approximation. However, there is another
theorem that it is valid within Generalized Kohn-Sham
model (GKS) that validates the use of E(HOMO as -I.
This does not hold for A and the LUMO, but it can be
said that A is equal to -E(HOMO) of the anion. From a
practical point of view, if the E(HOMO) of the anion
is equal to the E(LUMO) of the neutral, then this
counterpart of Koopmans' theorem will hold within DFT.
Indeed this is an approximation, and its accuracy will
be depending on the model chemistry chosen for your
calculations. In our research group, we have been
doing investigations to find the best model chemistry
that satisfies this approximation and our published
results show that the MN12SX/Def2TZVP/H20 reproduce
the values with great accuracy. Of course, there could
be another combinations that could help (including
tuned density functionals to get the desired Koopmans
behavior) but most of the usually recommended density
functionals are not useful in this regard.<br class="">
</blockquote>
<br class="">
Bartlett's "consistent DFT" should also be mentioned in
this context; their QTP functionals are obtained by
enforcing correct excitation spectra. See dois
10.1016/j.cplett.2016.12.017 and 10.1063/1.5116338.<br
class="">
-- <br class="">
------------------------------------------------------------------<br
class="">
Mr. Susi Lehtola, PhD Junior Fellow, Adjunct
Professor<br class="">
susi.lehtola() <a href="http://alumni.helsinki.fi"
class="" moz-do-not-send="true">alumni.helsinki.fi</a>
University of Helsinki<br class="">
<a href="http://susilehtola.github.io/" class=""
moz-do-not-send="true">http://susilehtola.github.io/</a>
Finland<br class="">
------------------------------------------------------------------<br
class="">
Susi Lehtola, dosentti, FT tutkijatohtori<br
class="">
susi.lehtola() <a href="http://alumni.helsinki.fi"
class="" moz-do-not-send="true">alumni.helsinki.fi</a>
Helsingin yliopisto<br class="">
<a href="http://susilehtola.github.io/" class=""
moz-do-not-send="true">http://susilehtola.github.io/</a><br
class="">
------------------------------------------------------------------<br
class="">
<br class="">
<br class="">
<br class=""<br class=""<br class="">
the strange characters on the top line to the /a\ sign.
You can also<br class=""<br
class="">
<br class="">
E-mail to subscribers: CHEMISTRY/a\ccl.net or use:<br
class="">
<a class="moz-txt-link-freetext" href="http://www.ccl.net/cgi-bin/ccl/send_ccl_message">http://www.ccl.net/cgi-bin/ccl/send_ccl_message</a><br
class="">
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E-mail to administrators: CHEMISTRY-REQUEST/a\ccl.net or
use<br class="">
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class="">
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<br class="">
Before posting, check wait time at: <a class="moz-txt-link-freetext" href="http://www.ccl.net">http://www.ccl.net</a><br
class="">
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<a class="moz-txt-link-freetext" href="http://server.ccl.net/chemistry/announcements/conferences/">http://server.ccl.net/chemistry/announcements/conferences/</a><br
class="">
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Search Messages:
<a class="moz-txt-link-freetext" href="http://www.ccl.net/chemistry/searchccl/index.shtml">http://www.ccl.net/chemistry/searchccl/index.shtml</a><br
class="">
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<a class="moz-txt-link-freetext" href="http://www.ccl.net/spammers.txt">http://www.ccl.net/spammers.txt</a><br class="">
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RTFI:
<a class="moz-txt-link-freetext" href="http://www.ccl.net/chemistry/aboutccl/instructions/">http://www.ccl.net/chemistry/aboutccl/instructions/</a><br
class="">
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</div>
</blockquote>
</div>
<br class="">
</div>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
Ar cieņu,
Igors Mihailovs
Zinātniskais asistents
Organisko materiālu laboratorija
LU Cietvielu fizikas institūts
Yours faithfully,
Igors Mihailovs
Research assistant
Laboratory of Organic Materials
Institute of Solid State Physics, University of Latvia</pre>
</body>
</html>
--------------91FB4B72A8623BEB6EEE1D17--
From owner-chemistry@ccl.net Tue Jan 7 12:32:01 2020
From: "mo.fateh*yahoo.com mo.fateh*yahoo.com" <owner-chemistry-*-server.ccl.net>
To: CCL
Subject: CCL: The best method to calculate the ionization potential of organic mol.
Message-Id: <-53930-200107122437-22399-hkt1vp8GKYT0J56TLz5UMg-*-server.ccl.net>
X-Original-From: "mo.fateh__yahoo.com" <mo.fateh__yahoo.com>
Content-Type: multipart/alternative;
boundary="----=_Part_12964228_752351891.1578417856889"
Date: Tue, 7 Jan 2020 17:24:16 +0000 (UTC)
MIME-Version: 1.0
Sent to CCL by: "mo.fateh::yahoo.com" [mo.fateh::yahoo.com]
------=_Part_12964228_752351891.1578417856889
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
Dear All,
I am just a beginner in the computation field. Now I am confused with the o=
pposite feedback from different experts. I am working on the design of orga=
nic corrosion inhibitors and want to calculate the I and A in order to furt=
her compute some global chemical descriptors. I=C2=A0 would like to know th=
e answer to these questions:
1- Should I calculate the ionization potential in the gas phase similar to =
the experimental conditions (PES)?2- What is the best DFT model chemistry (=
Functional + Basis set) to compute the I and A of organic molecules? I have=
the corresponding experimental data.3- How can I calculate the adiabatic i=
onization potential? I found two methods for doing this;=C2=A0(i) the first=
one:=C2=A0you must optimize the ion geometries as well as the neutral and =
take the total energy difference between them (both in the ground state).(i=
) the second one: the energy difference between the ground state of the opt=
imized neutral molecule and the optimized excited state (TD-DFT) cation.
Thanks,Mo=C2=A0
On Tuesday 7 January 2020, 16:04:17 GMT+2, Robert Molt r.molt.chemical.=
physics{:}gmail.com <owner-chemistry+/-ccl.net> wrote: =20
=20
1.) Dr. Lehtola=E2=80=99s suggestion is correct. A distinction should be m=
ade when saying that =E2=80=9CKoopmans=E2=80=99s theorem does not hold for =
DFT.=E2=80=9D Whether or not =E2=80=9Cthe true=E2=80=9D DFT should have Koo=
pmans=E2=80=99s theorem is a subject of some scholarly debate. Dr. Bartlett=
=E2=80=99s work is intended to be proof that a well-formulated DFT, with em=
phasis on enforcing physical constraints, can do this. This is meant to be =
in contrast to the zoo of highly parameterized KS-DFT functionals, which do=
badly poorly outside their parameterization range (the Minnesota functiona=
ls being an example which are stupendous at many, many things, then bizarre=
ly terrible in certain circumstances outside the standard comp chem goals).
2.) None of this is intended to argue that Dr. Bartlett=E2=80=99s work is o=
r is not the best you can do, accuracy -wise, right here right now.=C2=A0
3.) The original question has a false dichotomy. The original question comp=
ared adiabatic vs. relaxed excitations (re-optimizing the structure of the =
cation or not) asking which was =E2=80=9Cmore accurate.=E2=80=9D This is wr=
ong; my emphasis is intended for clarity, not to be pejorative. These corre=
spond to two totally different experimental situations. If you are trying t=
o model ionization energies, you should re-optimize the geometries iff you =
are comparing to experimental ionization energies where the system=E2=80=99=
s molecular geometry does have time to relax. The same is true that an adia=
batic ionization energy must be compared to an adiabatic ionization experim=
ent. Usually, people mean the adiabatic ionization energy if they do not qu=
alify what they mean (but one should specify). It would be inconsistent to =
use relaxed structures to compute adiabatic ionization energies.
One could argue to do this anyway, on the grounds of judicious cancellation=
of error; I am ignorant, personally, of how errors cancel, assuming a syst=
ematic error exists in the first place. However, in so much as the goal of =
our field is to compute the right answer for the right reasons, it is incon=
sistent.
On Jan 7, 2020, at 4:08 AM, Susi Lehtola susi.lehtola[*]helsinki.fi <owner-=
chemistry/a\ccl.net> wrote:
Sent to CCL by: Susi Lehtola [susi.lehtola a helsinki.fi]
On 1/7/20 12:26 AM, Daniel Glossman-Mitnik dglossman _ gmail.com wrote:
The Koopmans' theorem (note that it is Koopmans, not Koopman) does not (the=
oretically) hold within DFT and it has been always used as approximation. H=
owever, there is another theorem that it is valid within Generalized Kohn-S=
ham model (GKS) that validates the use of E(HOMO as -I. This does not hold =
for A and the LUMO, but it can be said that A is equal to -E(HOMO) of the a=
nion. From a practical point of view, if the E(HOMO) of the anion is equal =
to the E(LUMO) of the neutral, then this counterpart of Koopmans' theorem w=
ill hold within DFT. Indeed this is an approximation, and its accuracy will=
be depending on the model chemistry chosen for your calculations. In our r=
esearch group, we have been doing investigations to find the best model che=
mistry that satisfies this approximation and our published results show tha=
t the MN12SX/Def2TZVP/H20 reproduce the values with great accuracy. Of cour=
se, there could be another combinations that could help (including tuned de=
nsity functionals to get the desired Koopmans behavior) but most of the usu=
ally recommended density functionals are not useful in this regard.
Bartlett's "consistent DFT" should also be mentioned in this context; their=
QTP functionals are obtained by enforcing correct excitation spectra. See =
dois 10.1016/j.cplett.2016.12.017 and 10.1063/1.5116338.
--=20
------------------------------------------------------------------
Mr. Susi Lehtola, PhD =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0Junior Fellow, Adjunct Professor
susi.lehtola() alumni.helsinki.fi =C2=A0=C2=A0University of Helsinki
http://susilehtola.github.io/ =C2=A0=C2=A0=C2=A0=C2=A0Finland
------------------------------------------------------------------
Susi Lehtola, dosentti, FT =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0tutkij=
atohtori
susi.lehtola() alumni.helsinki.fi =C2=A0=C2=A0Helsingin yliopisto
http://susilehtola.github.io/
------------------------------------------------------------------
-=3D This is automatically added to each message by the mailing script =3D-the strange characters on the top line to the /a\ sign. You can alsoE-mail to subscribers: CHEMISTRY/a\ccl.net or use:
=C2=A0=C2=A0=C2=A0=C2=A0http://www.ccl.net/cgi-bin/ccl/send_ccl_message
E-mail to administrators: CHEMISTRY-REQUEST/a\ccl.net or use
=C2=A0=C2=A0=C2=A0=C2=A0http://www.ccl.net/cgi-bin/ccl/send_ccl_messageConferences: http://server.ccl.net/chemistry/a=
nnouncements/conferences/=C2=A0=C2=A0=C2=A0=C2=A0http://www.ccl.net/spammers.txt=20
------=_Part_12964228_752351891.1578417856889
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
<html><head></head><body><div class=3D"ydp31b1a7f7yahoo-style-wrap" style=
=3D"font-family: verdana, helvetica, sans-serif; font-size: 16px;"><div></d=
iv>
<div dir=3D"ltr" data-setdir=3D"false">Dear All,</div><div dir=3D"l=
tr" data-setdir=3D"false"><br></div><div dir=3D"ltr" data-setdir=3D"false">=
I am just a beginner in the computation field. Now I am confused with the o=
pposite feedback from different experts. I am working on the design of orga=
nic corrosion inhibitors and want to calculate the I and A in order to furt=
her compute some global chemical descriptors. I would like to know th=
e answer to these questions:</div><div dir=3D"ltr" data-setdir=3D"false"><b=
r></div><div dir=3D"ltr" data-setdir=3D"false">1- Should I calculate the io=
nization potential in the gas phase similar to the experimental conditions =
(PES)?</div><div dir=3D"ltr" data-setdir=3D"false">2- What is the best DFT =
model chemistry (Functional + Basis set) to compute the I and A of organic =
molecules? I have the corresponding experimental data.</div><div dir=3D"ltr=
" data-setdir=3D"false">3- How can I calculate the adiabatic ionization pot=
ential? I found two methods for doing this;</div><div dir=3D"ltr" data-setd=
ir=3D"false"> (i) the first one: <span><span style=3D"color: rgb(=
51, 51, 51); font-family: Montserrat, sans-serif; font-size: 15px;">you mus=
t optimize the ion geometries as well as the neutral and take the total ene=
rgy difference between them (both in the ground state).</span></span></div>=
<div dir=3D"ltr" data-setdir=3D"false"><span><span style=3D"color: rgb(51, =
51, 51); font-family: Montserrat, sans-serif; font-size: 15px;">(i) the sec=
ond one: the energy difference between the ground state of the optimized ne=
utral molecule and the optimized excited state (TD-DFT) cation.</span></spa=
n></div><div dir=3D"ltr" data-setdir=3D"false"><span><span style=3D"color: =
rgb(51, 51, 51); font-family: Montserrat, sans-serif; font-size: 15px;"><br=
></span></span></div><div dir=3D"ltr" data-setdir=3D"false"><span><span sty=
le=3D"color: rgb(51, 51, 51); font-family: Montserrat, sans-serif; font-siz=
e: 15px;">Thanks,</span></span></div><div dir=3D"ltr" data-setdir=3D"false"=
><span><span style=3D"color: rgb(51, 51, 51); font-family: Montserrat, sans=
-serif; font-size: 15px;">Mo </span></span></div><div dir=3D"ltr" data=
-setdir=3D"false"><br></div><div><br></div>
=20
</div><div id=3D"yahoo_quoted_8821319654" class=3D"yahoo_quoted">
<div style=3D"font-family:'Helvetica Neue', Helvetica, Arial, s=
ans-serif;font-size:13px;color:#26282a;">
=20
<div>
On Tuesday 7 January 2020, 16:04:17 GMT+2, Robert Molt =
r.molt.chemical.physics{:}gmail.com <owner-chemistry+/-ccl.net> wrote:
</div>
<div><br></div>
<div><br></div>
<div><div id=3D"yiv4765448473"><div>1.) Dr. Lehtola=E2=80=
=99s suggestion is correct. A distinction should be made when saying that =
=E2=80=9CKoopmans=E2=80=99s theorem does not hold for DFT.=E2=80=9D Whether=
or not =E2=80=9Cthe true=E2=80=9D DFT should have Koopmans=E2=80=99s theor=
em is a subject of some scholarly debate. Dr. Bartlett=E2=80=99s work is in=
tended to be proof that a well-formulated DFT, with emphasis on enforcing p=
hysical constraints, can do this. This is meant to be in contrast to the zo=
o of highly parameterized KS-DFT functionals, which do badly poorly outside=
their parameterization range (the Minnesota functionals being an example w=
hich are stupendous at many, many things, then bizarrely terrible in certai=
n circumstances outside the standard comp chem goals).<div class=3D"yiv4765=
448473"><br class=3D"yiv4765448473"></div><div class=3D"yiv4765448473">2.) =
None of this is intended to argue that Dr. Bartlett=E2=80=99s work is or is=
not the best you can do, accuracy -wise, right here right now. </div>=
<div class=3D"yiv4765448473"><br class=3D"yiv4765448473"></div><div class=
=3D"yiv4765448473">3.) The original question has a false dichotomy. The ori=
ginal question compared adiabatic vs. relaxed excitations (re-optimizing th=
e structure of the cation or not) asking which was =E2=80=9Cmore accurate.=
=E2=80=9D This is <b class=3D"yiv4765448473">wrong</b>; my emphasis is inte=
nded for clarity, not to be pejorative. These correspond to two totally dif=
ferent experimental situations. If you are trying to model ionization energ=
ies, you should re-optimize the geometries iff you are comparing to experim=
ental ionization energies where the system=E2=80=99s molecular geometry doe=
s have time to relax. The same is true that an adiabatic ionization energy =
must be compared to an adiabatic ionization experiment. Usually, people mea=
n the adiabatic ionization energy if they do not qualify what they mean (bu=
t one should specify). It would be inconsistent to use relaxed structures t=
o compute adiabatic ionization energies.</div><div class=3D"yiv4765448473">=
<br class=3D"yiv4765448473"></div><div class=3D"yiv4765448473">One could ar=
gue to do this anyway, on the grounds of judicious cancellation of error; I=
am ignorant, personally, of how errors cancel, assuming a systematic error=
exists in the first place. However, in so much as the goal of our field is=
to compute the right answer for the right reasons, it is inconsistent.<br =
class=3D"yiv4765448473"><div><br class=3D"yiv4765448473"><blockquote type=
=3D"cite" class=3D"yiv4765448473"><div class=3D"yiv4765448473">On Jan 7, 20=
20, at 4:08 AM, Susi Lehtola susi.lehtola[*]<a rel=3D"nofollow" target=3D"_=
blank" href=3D"http://helsinki.fi" class=3D"yiv4765448473">helsinki.fi</a> =
<<a rel=3D"nofollow" ymailto=3D"mailto:owner-chemistry/a\ccl.net" target=
=3D"_blank" href=3D"mailto:owner-chemistry/a\ccl.net" class=3D"yiv476544847=
3">owner-chemistry/a\ccl.net</a>> wrote:</div><br class=3D"yiv4765448473=
Apple-interchange-newline"><div class=3D"yiv4765448473"><div class=3D"yiv47=
65448473"><br class=3D"yiv4765448473">Sent to CCL by: Susi Lehtola [susi.le=
htola a <a rel=3D"nofollow" target=3D"_blank" href=3D"http://helsinki.fi" c=
lass=3D"yiv4765448473">helsinki.fi</a>]<br class=3D"yiv4765448473">On 1/7/2=
0 12:26 AM, Daniel Glossman-Mitnik dglossman _ <a rel=3D"nofollow" target=
=3D"_blank" href=3D"http://gmail.com" class=3D"yiv4765448473">gmail.com</a>=
wrote:<br class=3D"yiv4765448473"><blockquote type=3D"cite" class=3D"yiv47=
65448473">The Koopmans' theorem (note that it is Koopmans, not Koopman) doe=
s not (theoretically) hold within DFT and it has been always used as approx=
imation. However, there is another theorem that it is valid within Generali=
zed Kohn-Sham model (GKS) that validates the use of E(HOMO as -I. This does=
not hold for A and the LUMO, but it can be said that A is equal to -E(HOMO=
) of the anion. From a practical point of view, if the E(HOMO) of the anion=
is equal to the E(LUMO) of the neutral, then this counterpart of Koopmans'=
theorem will hold within DFT. Indeed this is an approximation, and its acc=
uracy will be depending on the model chemistry chosen for your calculations=
. In our research group, we have been doing investigations to find the best=
model chemistry that satisfies this approximation and our published result=
s show that the MN12SX/Def2TZVP/H20 reproduce the values with great accurac=
y. Of course, there could be another combinations that could help (includin=
g tuned density functionals to get the desired Koopmans behavior) but most =
of the usually recommended density functionals are not useful in this regar=
d.<br class=3D"yiv4765448473"></blockquote><br class=3D"yiv4765448473">Bart=
lett's "consistent DFT" should also be mentioned in this context; their QTP=
functionals are obtained by enforcing correct excitation spectra. See dois=
10.1016/j.cplett.2016.12.017 and 10.1063/1.5116338.<br class=3D"yiv4765448=
473">-- <br class=3D"yiv4765448473">---------------------------------------=
---------------------------<br class=3D"yiv4765448473">Mr. Susi Lehtola, Ph=
D J=
unior Fellow, Adjunct Professor<br class=3D"yiv4765448473">susi.lehtola() <=
a rel=3D"nofollow" target=3D"_blank" href=3D"http://alumni.helsinki.fi" cla=
ss=3D"yiv4765448473">alumni.helsinki.fi</a> University of Helsi=
nki<br class=3D"yiv4765448473"><a rel=3D"nofollow" target=3D"_blank" href=
=3D"http://susilehtola.github.io/" class=3D"yiv4765448473">http://susilehto=
la.github.io/</a> Finland<br class=3D"yiv4765448473=
">------------------------------------------------------------------<br cla=
ss=3D"yiv4765448473">Susi Lehtola, dosentti, FT &nb=
sp; tutkijatohtori<br class=3D"yiv4765448473">susi.lehtola() <a =
rel=3D"nofollow" target=3D"_blank" href=3D"http://alumni.helsinki.fi" class=
=3D"yiv4765448473">alumni.helsinki.fi</a> Helsingin yliopisto<b=
r class=3D"yiv4765448473"><a rel=3D"nofollow" target=3D"_blank" href=3D"htt=
p://susilehtola.github.io/" class=3D"yiv4765448473">http://susilehtola.gith=
ub.io/</a><br class=3D"yiv4765448473">-------------------------------------=
-----------------------------<br class=3D"yiv4765448473"><br class=3D"yiv47=
65448473"><br class=3D"yiv4765448473"><br class=3D"yiv4765448473">-=3D This=
is automatically added to each message by the mailing script =3D-<br class=
=3D"yiv4765448473">To recover the email address of the author of the messag=
e, please change<br class=3D"yiv4765448473">the strange characters on the t=
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e X-Original-From: line in the mail header.<br class=3D"yiv4765448473"><br =
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From owner-chemistry@ccl.net Tue Jan 7 16:16:00 2020
From: "Ronald Cook cookrl-,-tda.com" <owner-chemistry===server.ccl.net>
To: CCL
Subject: CCL: The best method to calculate the ionization potential of organic mol.
Message-Id: <-53931-200107160614-6633-zRHlqJ+jwygFrPpEvAbUNA===server.ccl.net>
X-Original-From: Ronald Cook <cookrl.:.tda.com>
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Date: Tue, 7 Jan 2020 14:05:56 -0700
MIME-Version: 1.0
Sent to CCL by: Ronald Cook [cookrl() tda.com]
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All this discussion seems somewhat academic to me. The first question to
really ask is if these are the right comnputed "features" to use. They are
not except for very limited and small datasets (see Winkler, D. A.,
Breedon, M., Hughes, A. E., Burden, F. R., Barnard, A. S., Harvey, T. G., &
Cole, I. (2014). Towards chromate-free corrosion inhibitors:
structure-property models for organic alternatives. *Green Chemistry*, *16*=
(6),
3349-3357). A better approach is to ask what are the physical properties
that drive corrosion inhibition by organics. Organic corrosion inhibitors
protect by blocking active corrosion sites through adsorption. The
relationship that is most often observed for inhibition efficiency and
coverage is the Langmuir isotherm. With some simple math, we can show that
the Langmuir isotherm coverage is related to the free energy of
adsorption. In using IP and EA the way you were talking about using them
you are just computing the chemical hardness and the absolute
electronegativity (and then maybe using them to estimate the partial
transfer of electrons between the metal and the organic; Parrs delta N).
At best these might describe the bonding energetics (delta H) of
adsorption, You are ignoring (at your modeling peril) the entropy of
adsorption (T delta S). Kuhne (see K=C3=BChne, R., Franke, R., Dittrich, J=
., &
Kretschmer, E. (1983). Relationship between Polarographic Adsorption Data
and Hydrophobicity. *Quantitative Structure=E2=80=90Activity Relationships*=
, *2*(1),
20-21.) has shown that significant energies of adsorption (on mercury
electrodes where the polar ends face the water and Delt H is small) are
driven by hydrophobicity (LogP). Also, you need to consider speciation and
how it affects Delta H and T delta S (LogP). For the latter, going from a
neutral to charged species can change LogP 3 to 5 fold. Such effects can
swamp the small effects of how you compute IP, EA
Ron Cook
On Mon, Jan 6, 2020 at 7:00 AM Mo Fateh mo.fateh]*[yahoo.com <
owner-chemistry[#]ccl.net> wrote:
>
> Sent to CCL by: "Mo Fateh" [mo.fateh ~ yahoo.com]
> Dear CCL subscribers,
>
> I want to calculate the global reactivity parameters of some organic
> molecules as corrosion inhibitors. As you know, these parameters depends
> on
> the ionization potential and electron affinity. For example, the absolute
> hardness can be computed through this equation: =3D((I-A))/2 where I and =
A
> are ionization potential and electron affinity, respectively. The survey
> on
> how to calculate I and A using DFT method yielded three methods of
> computation.
>
> 1- Koopman method (e.g. I =3D -E(HOMO) & A =3D-E(LUMO)
> 2- Vertical method (e.g. I=3DE(N-1)- E(N) at fixed geometry)
> 3- Adiabatic method (e.g. I=3DE(N-1)- E(N) at optimized geometries)
>
> Which one is the most reliable in such project?
>
> Regards,
> MO
>
>
>
> -=3D This is automatically added to each message by the mailing script =
=3D->
>
>
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<div dir=3D"ltr"><div class=3D"gmail_default" style=3D"font-family:tahoma,s=
ans-serif;font-size:small">All this discussion seems somewhat academic to m=
e.=C2=A0 The first question to really ask is if these are the right comnput=
ed "features" to use.=C2=A0 They are not except for very limited =
and small datasets (see=C2=A0<span style=3D"font-size:13px;font-family:Aria=
l,sans-serif">Winkler, D. A., Breedon, M., Hughes, A. E., Burden, F. R., Ba=
rnard, A. S., Harvey, T. G., & Cole, I. (2014). Towards chromate-free c=
orrosion inhibitors: structure-property models for organic alternatives.=C2=
=A0</span><i style=3D"font-size:13px;font-family:Arial,sans-serif">Green Ch=
emistry</i><span style=3D"font-size:13px;font-family:Arial,sans-serif">,=C2=
=A0</span><i style=3D"font-size:13px;font-family:Arial,sans-serif">16</i><s=
pan style=3D"font-size:13px;font-family:Arial,sans-serif">(6), 3349-3357).=
=C2=A0 A better approach is to ask what are the physical properties that dr=
ive corrosion inhibition by organics. Organic corrosion inhibitors protect =
by blocking active corrosion sites through adsorption.=C2=A0 The relationsh=
ip that is most often observed for inhibition efficiency and coverage is th=
e Langmuir isotherm. With some simple math, we can show that the Langmuir i=
sotherm coverage is related to the free energy of adsorption.=C2=A0 In usin=
g IP and EA</span>=C2=A0the way you were talking about using them you are j=
ust computing the chemical hardness and the absolute electronegativity (and=
then maybe using them to estimate the partial transfer of electrons betwee=
n the metal and the organic; Parrs delta N).=C2=A0 At best these might desc=
ribe the bonding energetics (delta H) of adsorption,=C2=A0 You are ignoring=
(at your modeling peril) the entropy of adsorption (T delta S).=C2=A0 Kuhn=
e (see=C2=A0<span style=3D"font-size:13px;font-family:Arial,sans-serif">K=
=C3=BChne, R., Franke, R., Dittrich, J., & Kretschmer, E. (1983). Relat=
ionship between Polarographic Adsorption Data and Hydrophobicity.=C2=A0</sp=
an><i style=3D"font-size:13px;font-family:Arial,sans-serif">Quantitative St=
ructure=E2=80=90Activity Relationships</i><span style=3D"font-size:13px;fon=
t-family:Arial,sans-serif">,=C2=A0</span><i style=3D"font-size:13px;font-fa=
mily:Arial,sans-serif">2</i><span style=3D"font-size:13px;font-family:Arial=
,sans-serif">(1), 20-21.) has shown that significant energies of adsorption=
(on mercury electrodes where the polar ends face the water and Delt H is s=
mall) are driven by hydrophobicity (LogP).=C2=A0 Also, you need to consider=
speciation and how it affects Delta H and T delta S (LogP).=C2=A0 For the =
latter, going from a neutral to charged species can change LogP 3 to 5 fold=
.=C2=A0 Such effects can swamp the small effects of how you compute IP, EA<=
/span>=C2=A0</div><div class=3D"gmail_default" style=3D"font-family:tahoma,=
sans-serif;font-size:small"><br></div><div class=3D"gmail_default" style=3D=
"font-family:tahoma,sans-serif;font-size:small">Ron Cook</div></div><br><di=
v class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_attr">On Mon, Jan 6=
, 2020 at 7:00 AM Mo Fateh mo.fateh]*[<a href=3D"http://yahoo.com">yahoo.co=
m</a> <<a href=3D"mailto:owner-chemistry[#]ccl.net">owner-chemistry[#]ccl.ne=
t</a>> wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin=
:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"=
><br>
Sent to CCL by: "Mo=C2=A0 Fateh" [mo.fateh ~ <a href=3D"http://ya=
hoo.com" rel=3D"noreferrer" target=3D"_blank">yahoo.com</a>]<br>
Dear CCL subscribers,<br>
<br>
I want to calculate the global reactivity parameters of some organic <br>
molecules as corrosion inhibitors. As you know, these parameters depends on=
<br>
the ionization potential and electron affinity. For example, the absolute <=
br>
hardness can be computed through this equation: =3D((I-A))/2 where I and A =
<br>
are ionization potential and electron affinity, respectively. The survey on=
<br>
how to calculate I and A using DFT method yielded three methods of <br>
computation.<br>
<br>
1- Koopman method (e.g. I =3D -E(HOMO) & A =3D-E(LUMO)<br>
2- Vertical method (e.g. I=3DE(N-1)- E(N) at fixed geometry)<br>
3- Adiabatic method (e.g. I=3DE(N-1)- E(N) at optimized geometries)<br>
<br>
Which one is the most reliable in such project?<br>
<br>
Regards,<br>
MO<br>
<br>
<br>
<br>
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