CCL:G: Question on calculation of charge center of electrons in a molecule

2010/11/29 John McKelvey jmmckel-,-gmail.com <owner-chemistry..ccl.net>

Sent to CCL by: John McKelvey [jmmckel++gmail.com]
On the other hand the NBO program can compute ZDO type charges which
are atom-centered and are along the diagonal of the density matrix and
for which the sum is the same as the number of electrons in the
system.

John McKelvey

On Mon, Nov 29, 2010 at 10:01 AM, James Eilers jeilers!^!siue.edu

<owner-chemistry],[ccl.net> wrote:
> Mulliken charges also include the "shared" electron density or cross terms
> between atomic orbitals on different centers.
>
> On Nov 27, 2010, at 8:02 PM, Jiabo Li jiaboli/./yahoo.com wrote:
>
>> To understand what is wrong, you can look at a simple example: the
>> hydrogen atom in its excited state with the single electron on a SP hydride
>> orbital. In this case, the electron density is not central symmetric but
>> polarized, and the dipole moment is not zero (a big dipole moment), while in
>> this case the net atomic charge is zero (neutral).
>>
>> Jiabo
>>
>> --- On Fri, 11/26/10, Herbert Fruchtl herbert.fruchtl[#]st-andrews.ac.uk
>> <owner-chemistry]*[ccl.net> wrote:
>>
>>
>>> From: Herbert Fruchtl herbert.fruchtl[#]st-andrews.ac.uk
>>> <owner-chemistry]*[ccl.net>
>>
>> Subject: CCL:G: Question on calculation of charge center of electrons in a
>> molecule
>> To: "Li, Jiabo " <jiaboli]*[yahoo.com>
>> Date: Friday, November 26, 2010, 6:25 AM
>>
>>
>>
>> Sent to CCL by: Herbert Fruchtl [herbert.fruchtl::st-andrews.ac.uk]
>> The centre of charge of each Gaussian function is its origin, i.e. the
>> nucleus if you have atom-centred basis functions. The Mulliken charge is the
>> sum of those functions, multiplied with their occupation number. Shouldn't
>> this sum have its centre on the nucleus as well? And the sum of all of them
>> (over all atoms) gives the complete charge distribution. Where am I going
>> wrong?
>>
>> Herbert
>>
>> Ulf Ekström ulfek(~)few.vu.nl wrote:
>>>
>>> Sent to CCL by: =?ISO-8859-1?Q?Ulf_Ekstr=F6m?= [ulfek],[few.vu.nl]
>>> On Thu, Nov 25, 2010 at 9:56 AM, Herbert Fruchtl
>>> herbert.fruchtl-.-st-andrews.ac.uk <owner-chemistry . ccl.net> wrote:
>>>>
>>>> Sent to CCL by: Herbert Fruchtl [herbert.fruchtl*_*st-andrews.ac.uk]
>>>> I don't have time to look at the maths of it, but I think the centre of
>>>> charge of the electron density should be identical to the centre of the
>>>> Mulliken charges, which would be easy to calculate (analogous to the
>>>> centre
>>>> of mass).
>>>
>>> This will not work, for example if you have a single centre basis set all
>>> Mulliken charge would be on that center. What you should do is to compute
>>> the dipole moment of the molecule and use that to work out the center
>>> of charge.
>>>
>>> Sincerely,
>>> Ulf Ekstrom>
>>
>> -- Herbert Fruchtl
>> Senior Scientific Computing Officer
>> School of Chemistry, School of Mathematics and Statistics
>> University of St Andrews
>> --
>> The University of St Andrews is a charity registered in Scotland:

>> No SC013532>> http://www.ccl.net/cgi-bin/ccl/send_ccl_message

>> http://www.ccl.net/cgi-bin/ccl/send_ccl_message
>>
>> Subscribe/Unsubscribe: Conferences:
>> http://server.ccl.net/chemistry/announcements/conferences/
>> http://www.ccl.net/spammers.txt--0-160776249-1290909739=:87851
>> Content-Type: text/html; charset=iso-8859-1
>> Content-Transfer-Encoding: quoted-printable
>>
>> <table cellspacing="0" cellpadding="0" border="0" ><tr><td valign="top"
>> style="font: inherit;"><DIV>To understand what is wrong, you can look at a
>> simple example: the hydrogen atom in its excited state with the single
>> electron on a SP hydride orbital. In this case, the electron density is not
>> central symmetric but polarized, and the dipole moment is not zero (a big
>> dipole moment), while in this case the net atomic charge is zero
>> (neutral).</DIV>
>> <DIV> </DIV>
>> <DIV>Jiabo --- On Fri, 11/26/10, Herbert Fruchtl
>> herbert.fruchtl[#]st-andrews.ac.uk
>> <owner-chemistry]*[ccl.net> wrote: </DIV>
>> <BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT:
>> rgb(16,16,255) 2px solid"> From: Herbert Fruchtl
>> herbert.fruchtl[#]st-andrews.ac.uk
>> <owner-chemistry]*[ccl.net> Subject: CCL:G: Question on calculation
>> of charge center of electrons in a molecule To: "Li, Jiabo "
>> <jiaboli]*[yahoo.com> Date: Friday, November 26, 2010, 6:25
>> AM 
>> <DIV class=plainMail> Sent to CCL by: Herbert Fruchtl
>> [herbert.fruchtl::st-andrews.ac.uk] The centre of charge of each Gaussian
>> function is its origin, i.e. the nucleus if you have atom-centred basis
>> functions. The Mulliken charge is the sum of those functions, multiplied
>> with their occupation number. Shouldn't this sum have its centre on the
>> nucleus as well? And the sum of all of them (over all atoms) gives the
>> complete charge distribution. Where am I going wrong?  
>> Herbert Ulf Ekström ulfek(~)few.vu.nl wrote: > Sent to CCL by:
>> =?ISO-8859-1?Q?Ulf_Ekstr=F6m?= [ulfek],[few.vu.nl] > On Thu, Nov 25,
>> 2010 at 9:56 AM, Herbert Fruchtl > herbert.fruchtl-.-st-andrews.ac.uk
>> <owner-chemistry . ccl.net> wrote: >> Sent to CCL by: Herbert
>> Fruchtl [herbert.fruchtl*_*st-andrews.ac.uk] >> I don't have time
>> to look at the maths of it, but I think the centre of >> charge of
>> the electron density
>> should be identical to the centre of the >> Mulliken charges,
>> which would be easy to calculate (analogous to the centre >> of
>> mass). > > This will not work, for example if you have a single
>> centre basis set all > Mulliken charge would be on that center. What
>> you should do is to compute > the dipole moment of the molecule and
>> use that to work out the center > of charge. > >
>> Sincerely, > Ulf Ekstrom> -- Herbert Fruchtl Senior
>> Scientific Computing Officer School of Chemistry, School of Mathematics
>> and Statistics University of St Andrews -- The University of St
>> Andrews is a charity registered in Scotland: No
>> SC013532 -= This is automatically added to each message by
>> the mailing script =- To recover the email address of the author of the
>> message, please change the strange characters on the top line to the ]*[
>> sign. You can also<BR E-mail to subscribers: <A
>> href="" href="http://us.mc369.mail.yahoo.com/mc/compose?to=CHEMISTRY]*[ccl.net" target="_blank">http://us.mc369.mail.yahoo.com/mc/compose?to=CHEMISTRY]*[ccl.net"
>> ymailto="mailto:CHEMISTRY]*[ccl.net">CHEMISTRY]*[ccl.net</A> or
>> use:      <A
>> href="" 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="" href="http://us.mc369.mail.yahoo.com/mc/compose?to=CHEMISTRY-REQUEST]*[ccl.net" target="_blank">http://us.mc369.mail.yahoo.com/mc/compose?to=CHEMISTRY-REQUEST]*[ccl.net"
>> ymailto="mailto:CHEMISTRY-REQUEST]*[ccl.net">CHEMISTRY-REQUEST]*[ccl.net</A>
>> or use      <A
>> href="" 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> Subscribe/Unsubscribe: 
>>     <A href="" 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="" href="http://www.ccl.net/" target="_blank">http://www.ccl.net/"
>> target=_blank>http://www.ccl.net</A> Job: <A
>> href="" href="http://www.ccl.net/jobs" target="_blank">http://www.ccl.net/jobs" target=_blank>http://www.ccl.net/jobs</A>
>> Conferences: <A
>> href="" 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="" href="http://www.ccl.net/chemistry/searchccl/index.shtml" target="_blank">http://www.ccl.net/chemistry/searchccl/index.shtml"
>> target=_blank>http://www.ccl.net/chemistry/searchccl/index.shtml</A> <BR  
>>    <A href="" 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="" href="http://www.ccl.net/chemistry/aboutccl/instructions/" target="_blank">http://www.ccl.net/chemistry/aboutccl/instructions/"
>> target=_blank>http://www.ccl.net/chemistry/aboutccl/instructions/</A> </DIV></BLOCKQUOTE></td></tr></table>
>
> James E. Eilers
> Professor
> Chemistry Department
> Southern Illinois University Edwardsville
> (618)650-3559
>

--
John McKelvey
10819 Middleford Pl
Ft Wayne, IN 46818
260-489-2160
jmmckel],[gmail.com

-= This is automatically added to each message by the mailing script =-

To recover the email address of the author of the message, please change

the strange characters on the top line to the .. sign. You can also

E-mail to subscribers: CHEMISTRY..ccl.net or use:

http://www.ccl.net/cgi-bin/ccl/send_ccl_message

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

http://www.ccl.net/cgi-bin/ccl/send_ccl_message

Subscribe/Unsubscribe:

http://www.ccl.net/chemistry/sub_unsub.shtml

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

Job: http://www.ccl.net/jobs

Conferences: http://server.ccl.net/chemistry/announcements/conferences/

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

http://www.ccl.net/spammers.txt

RTFI: http://www.ccl.net/chemistry/aboutccl/instructions/