just to add again on thuis issue: Some (most?) anions have positive
homo energies. I suppose this means they do not really exist in
isolation. I wonder what the correct way of calculating
the energis in solution for such species would be. I was thinking of I
want to calculate the energy of an anionic species, A-(aq), then I
can consider the cycle:
AH = A-(aq) +H+(aq). Both AH (which is neutral) and H+ obviously hav
epositive homos and so can be considered stable, so E(AH-H+(aq)) can be
considered the true energy of A- in solution, and it may/may not differ from a
direct calculation of a hypothetical A- in solution. But then, the energy of A-
can easily depend on the nature of the counterion. Is that not a true picture of
reality, i.e. energy of an anion in solution should depend on the nature of the
surounding cation (even if it is not strongly bound)?
I hope the argument that species with positive HOMOs (think HF
energies to avoid the issue of meaning of DFT orbitals) do not exist
is true irrespective of the belief about whether orbitals are reality
or not (i do not want to re-start that debate).
Sent to CCL by:
nokophala-$-aim.com
----------MailBlocks_8C7FA093983A4F3_1630_19F3_FWM-D25.sysops.aol.com
Content-Type: text/plain; charset="us-ascii"
Thanks for responses so far, everyone. From my current calcs it does seem that
one must have the correct structure of the first shell, especially for cationic
ions. For H+ is is almost mandatory, but already a single water molecules brings
the solvation energy to within an eV of the correct value. Anionic species seem
ok'yish even without a shell.
Dr Noko Phala
E-mail: nokophala ~~ aim.com
-----Original Message-----
> From: Goedele Roos groos[]vub.ac.be <owner-chemistry ~~ ccl.net>
To: Phala, Noko <nokophala ~~ aim.com>
Sent: Mon, 6 Feb 2006 14:54:03 -0500
Subject: CCL: Aquous electrochemistry
Sent to CCL by: Goedele Roos [groos^-^vub.ac.be]
Yes, the first solvatation shell is important,
see Uudsemaa, M., Tamm, T., J. Phys. Chem. A 2003, 107, 9997.
or see: M. Namazian, Siahrostami, s., Noorbala, M. R., Coote, m. L., J. Mol.
Struct.: Theochem, 759,(2006), 245.
or: Shamsipur, M., Alizadeh, Arshadi, S., J. Mol. Struct.: Theochem, 758,
(2005), 71
also a very good paper Dutton, A., S., Fukuto, J. M., Kendall, N. H., J. Inorg.
Chem. 2005, 44, 4024.
Baik, M.-H., Friesner, A. J. Phys. Chem. A 2002, 106, 7407.
Patterson, E, Cramer, C., Truhlar, D, JACS, 123 (2001) 2025.
Greetz, Goedele
>Sent to CCL by: "Jim Kress" [ccl_nospam#kressworks.com]
>Here's an interesting link:
>
>http://comp.chem.umn.edu/netstep/2000/february/9truhcram.html
>
>
>Jim
>
>> -----Original Message-----
>> From: nokophala. ~ .aim.com [mailto:owner-chemistry ~
ccl.net]
>> Sent: Sunday, February 05, 2006 10:22 AM
>> To: Kress, Jim
>> Subject: CCL: Aquous electrochemistry
>>
>> Sent to CCL by: nokophala++aim.com
>>
>> Hi There,
>> Is anyone aware of successes in reproducing some of the
>> tabulated redox potentials of electrochemical reactions that
>> ar elisted i standard electrochemical tables, especiall those
>> involving single ions? e.g. Cu
>> --> Cu2+(aq) + 2e-. The key issue that I need coment on here is the
>> selection of appropriate solvation models. I doubt if
>> continuum models would require inclusion of at least the
>> first shell of water molecules, as these are strongly bound.
>> As a starting point I am trying to reproduce the experimental
>> value of the 'reference' reaction 2H+ +2e = H2. Even this
>> appears tricky.
>>
>> Thanks in advance,
>>
>> Noko Phala, Anglo Research
>> ______________________________________________________________
>> __________
>> Check Out the new free AIM(R) Mail -- 2 GB of storage and
>> industry-leading spam and email virus protection.
>>
>>
>>
>> -= This is automatically added to each message by the mailing
>> script =-
>> To recover the email address of the author of the message,
>> please change> Conferences:
>> http://server.ccl.net/chemistry/announcements/conferences/
>>
>> Search Messages: http://www.ccl.net/htdig (login: ccl,
>> Password: search)>
>> -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>> -+-+-+-+-+>
>
>
>
Drs. Goedele Roos
Dienst Algemene Chemie (ALGC)
Vrije Universiteit Brussel (VUB)
Pleinlaan 2
B-1050 Brussels
Tel: 0032-2-629 35 16
Fax: 0032-2-629 33 17http-:-//www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp://www.ccl.net/chemistry/sub_unsub.shtmlhttp://www.ccl.net/spammers.txt________________________________________________________________________
Check Out the new free AIM(R) Mail -- 2 GB of storage and industry-leading spam
and email virus protection.
----------MailBlocks_8C7FA093983A4F3_1630_19F3_FWM-D25.sysops.aol.com
Content-Type: text/html; charset="us-ascii"
<HTML><BODY><DIV style='font-family: "Verdana"; font-size:
10pt;'><DIV>
<DIV>Thanks for responses so far, everyone. From my current calcs it does
seem
that one must have the correct structure of the first shell, especially for
cationic ions. For H+ is is almost mandatory, but already a single water
molecules brings the solvation energy to within an eV of the correct value.
Anionic species seem ok'yish even without a shell. </DIV>
<DIV> </DIV>
<DIV><BR><BR><BR>Dr Noko Phala<BR>E-mail:
nokophala ~~ aim.com<BR></DIV>
<DIV> </DIV> <BR>-----Original Message-----<BR>From:
Goedele Roos
groos[]vub.ac.be <owner-chemistry ~~ ccl.net><BR>To: Phala, Noko
<nokophala ~~
aim.com><BR>Sent: Mon, 6 Feb 2006 14:54:03 -0500<BR>Subject: CCL:
Aquous
electrochemistry<BR><BR>
<STYLE>
.AOLPlainTextBody {
margin: 0px;
font-family: Tahoma, Verdana, Arial, Sans-Serif;
font-size: 12px;
color: #000;
background-color: #fff;
}
.AOLPlainTextBody pre {
font-size: 9pt;
}
.AOLInlineAttachment {
margin: 10px;
}
.AOLAttachmentHeader {
border-bottom: 2px solid #E9EAEB;
background: #F9F9F9;
}
.AOLAttachmentHeader .Title {
font: 11px Tahoma;
font-weight: bold;
color: #666666;
background: #E9EAEB;
padding: 3px 0px 1px 10px;
}
.AOLAttachmentHeader .FieldLabel {
font: 11px Tahoma;
font-weight: bold;
color: #666666;
padding: 1px 10px 1px 9px;
}
.AOLAttachmentHeader .FieldValue {
font: 11px Tahoma;
color: #333333;
}
</STYLE>
<DIV class=AOLPlainTextBody
id=AOLMsgPart_0_5b1d94a5-e3d2-4048-b182-b236a00316f8><PRE><TT>Sent
to CCL by: Goedele Roos [groos^-^vub.ac.be]
Yes, the first solvatation shell is important,
see Uudsemaa, M., Tamm, T., J. Phys. Chem. A 2003, 107, 9997.
or see: M. Namazian, Siahrostami, s., Noorbala, M. R., Coote, m. L., J. Mol.
Struct.: Theochem, 759,(2006), 245.
or: Shamsipur, M., Alizadeh, Arshadi, S., J. Mol. Struct.: Theochem, 758,
(2005), 71
also a very good paper Dutton, A., S., Fukuto, J. M., Kendall, N. H., J. Inorg.
Chem. 2005, 44, 4024.
Baik, M.-H., Friesner, A. J. Phys. Chem. A 2002, 106, 7407.
Patterson, E, Cramer, C., Truhlar, D, JACS, 123 (2001) 2025.
Greetz, Goedele
>Sent to CCL by: "Jim Kress" [ccl_nospam#kressworks.com]
>Here's an interesting link:
>
><A href=""http://comp.chem.umn.edu/netstep/2000/february/9truhcram.html"
target=_blank>http://comp.chem.umn.edu/netstep/2000/february/9truhcram.html"
target=_blank>http://comp.chem.umn.edu/netstep/2000/february/9truhcram.html</A>
>
>
>Jim
>
>> -----Original Message-----
>> From: nokophala. ~ .aim.com [<A
href=""mailto:owner-chemistry%5cx22%3emailto%3aowner-chemistry%3c%2fA">mailto:owner-chemistry">mailto:owner-chemistry</A>
~ ccl.net]
>> Sent: Sunday, February 05, 2006 10:22 AM
>> To: Kress, Jim
>> Subject: CCL: Aquous electrochemistry
>>
>> Sent to CCL by: nokophala++aim.com
>>
>> Hi There,
>> Is anyone aware of successes in reproducing some of the
>> tabulated redox potentials of electrochemical reactions that
>> ar elisted i standard electrochemical tables, especiall those
>> involving single ions? e.g. Cu
>> --> Cu2+(aq) + 2e-. The key issue that I need coment on here is the
>> selection of appropriate solvation models. I doubt if
>> continuum models would require inclusion of at least the
>> first shell of water molecules, as these are strongly bound.
>> As a starting point I am trying to reproduce the experimental
>> value of the 'reference' reaction 2H+ +2e = H2. Even this
>> appears tricky.
>>
>> Thanks in advance,
>>
>> Noko Phala, Anglo Research
>> ______________________________________________________________
>> __________
>> Check Out the new free AIM(R) Mail -- 2 GB of storage and
>> industry-leading spam and email virus protection.
>>
>>
>>
>> -= This is automatically added to each message by the mailing
>> script =-
>> To recover the email address of the author of the message,
>> please change> Conferences:
>> <A
href=""http://server.ccl.net/chemistry/announcements/conferences/"
target=_blank>http://server.ccl.net/chemistry/announcements/conferences/"
target=_blank>http://server.ccl.net/chemistry/announcements/conferences/</A>
>>
>> Search Messages: <A href=""http://www.ccl.net/htdig"
target=_blank>http://www.ccl.net/htdig" target=_blank>http://www.ccl.net/htdig</A>
(login: ccl,
>> Password: search)>
>> -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>> -+-+-+-+-+>
>
>
>
Drs. Goedele Roos
Dienst Algemene Chemie (ALGC)
Vrije Universiteit Brussel (VUB)
Pleinlaan 2
B-1050 Brussels
Tel: 0032-2-629 35 16
Fax: 0032-2-629 33 17E-mail to subscribers: <A
href=""mailto:CHEMISTRY%2540ccl.net%5cx22%3eCHEMISTRY">mailto:CHEMISTRY%40ccl.net">CHEMISTRY
~~ ccl.net</A> or use:
<A href=""http://www.ccl.net/cgi-bin/ccl/send_ccl_message"
target=_blank>http://www.ccl.net/cgi-bin/ccl/send_ccl_message"
target=_blank>http://www.ccl.net/cgi-bin/ccl/send_ccl_message</A>
E-mail to administrators: <A
href=""mailto:CHEMISTRY-REQUEST%2540ccl.net%5cx22%3eCHEMISTRY-REQUEST">mailto:CHEMISTRY-REQUEST%40ccl.net">CHEMISTRY-REQUEST
~~ ccl.net</A> or use
<A href=""http://www.ccl.net/cgi-bin/ccl/send_ccl_message"
target=_blank>http://www.ccl.net/cgi-bin/ccl/send_ccl_message"
target=_blank>http://www.ccl.net/cgi-bin/ccl/send_ccl_message</A<A
href=""http://www.ccl.net/chemistry/sub_unsub.shtml"
target=_blank>http://www.ccl.net/chemistry/sub_unsub.shtml"
target=_blank>http://www.ccl.net/chemistry/sub_unsub.shtml</A>
Before posting, check wait time at: <A href=""http://www.ccl.net"
target=_blank>http://www.ccl.net"
target=_blank>http://www.ccl.net</A>
Job: <A href=""http://www.ccl.net/jobs"
target=_blank>http://www.ccl.net/jobs" target=_blank>http://www.ccl.net/jobs</A>
Conferences: <A
href=""http://server.ccl.net/chemistry/announcements/conferences/"
target=_blank>http://server.ccl.net/chemistry/announcements/conferences/"
target=_blank>http://server.ccl.net/chemistry/announcements/conferences/</A>
Search Messages: <A href=""http://www.ccl.net/htdig"
target=_blank>http://www.ccl.net/htdig" target=_blank>http://www.ccl.net/htdig</A>
(login: ccl, Password: search)<A href=""http://www.ccl.net/spammers.txt"
target=_blank>http://www.ccl.net/spammers.txt"
target=_blank>http://www.ccl.net/spammers.txt</A>
RTFI: <A href=""http://www.ccl.net/chemistry/aboutccl/instructions/"
target=_blank>http://www.ccl.net/chemistry/aboutccl/instructions/"
target=_blank>