Questions about dipole moments

General Discussion
1

Dear List Members,
I am building some simple molecules in Avogadro for a future lab
experiment. I built carbon dioxide by selecting carbon and a double bond
order, and I turned off the adjust hydrogens box. I created C = C = C, went
back and selected oxygen, and clicked on the outer carbon atoms to make
CO2. Once that was complete, I optimized the geometry using UFF. The bond
angle and lengths seem to be appropriate (180 degrees and 1.196 A for both
bonds), however the dipole moment seems abnormally large (7.893 D). The
patial charges seem right (-0.19 for each oxygen and 0.37 for the carbon
atom). Any ideas why I’m not getting close to a zero dipole moment?
Thanks,
Steve

2

There’s a bug where the dipole moment doesn’t get updated properly. What version are you using?

Thanks,
-Geoff

Prof. Geoffrey Hutchison
Department of Chemistry
University of Pittsburgh
tel: (412) 648-0492
email: geoff.hutchison@gmail.com
web: http://hutchison.chem.pitt.edu/

On Dec 10, 2012, at 2:12 AM, Steven Petrovic petrovis@sou.edu wrote:

Dear List Members,
I am building some simple molecules in Avogadro for a future lab experiment. I built carbon dioxide by selecting carbon and a double bond order, and I turned off the adjust hydrogens box. I created C = C = C, went back and selected oxygen, and clicked on the outer carbon atoms to make CO2. Once that was complete, I optimized the geometry using UFF. The bond angle and lengths seem to be appropriate (180 degrees and 1.196 A for both bonds), however the dipole moment seems abnormally large (7.893 D). The patial charges seem right (-0.19 for each oxygen and 0.37 for the carbon atom). Any ideas why I’m not getting close to a zero dipole moment?
Thanks,
Steve

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3

Hi Geoff,
I am currently using 1.0.3 from the Ubuntu repository. I do have version
1.1.0 on a PC, but I don’t recall whether I have the same problem with that
version of Avogadro. Is there a particular version that you know of that
provides an expected dipole moment of close to 0 Debyes?
Thanks,
Steve

On Mon, Dec 10, 2012 at 6:55 AM, Geoffrey Hutchison geoff.hutchison@gmail.com wrote:

There’s a bug where the dipole moment doesn’t get updated properly. What
version are you using?

Thanks,
-Geoff

Prof. Geoffrey Hutchison
Department of Chemistry
University of Pittsburgh
tel: (412) 648-0492
email: geoff.hutchison@gmail.com
web: http://hutchison.chem.pitt.edu/

On Dec 10, 2012, at 2:12 AM, Steven Petrovic petrovis@sou.edu wrote:

Dear List Members,
I am building some simple molecules in Avogadro for a future lab
experiment. I built carbon dioxide by selecting carbon and a double bond
order, and I turned off the adjust hydrogens box. I created C = C = C, went
back and selected oxygen, and clicked on the outer carbon atoms to make
CO2. Once that was complete, I optimized the geometry using UFF. The bond
angle and lengths seem to be appropriate (180 degrees and 1.196 A for both
bonds), however the dipole moment seems abnormally large (7.893 D). The
patial charges seem right (-0.19 for each oxygen and 0.37 for the carbon
atom). Any ideas why I’m not getting close to a zero dipole moment?
Thanks,
Steve

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avogadro-discuss List Signup and Options

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–
Dr. Steven Petrovic
Professor of Chemistry
Southern Oregon University
1250 Siskiyou Blvd.
Ashland, OR 97520
(541) 552-6803