Noel - do some of the other Open Babel force fields do a better job at this?
Marcus On Mon, Jan 21, 2013 at 8:59 AM, Noel O'Boyle <baoille...@gmail.com> wrote: > To be clear, are you asking why MMFF94 is so poor at predicting dipole > moments? > > - Noel > > On 19 January 2013 17:31, Steven Petrovic <petro...@sou.edu> wrote: >> Hello, >> Despite how wonderful I think Avogadro is for molecular modeling and its >> potential for educational purposes, I hesitate to use Avogadro in the >> chemistry laboratory when there seems to be such glaring issues as >> predicting the dipole moment for simple inorganic molecules such as carbon >> dioxide. When I build carbon dioxide using either 1.0.3 (in Ubuntu) or 1.1.0 >> (on a PC) and optimize the geometry using MMFF94, the bond lengths are the >> same (1.197 angstroms for each C=O bond) and the bond angle is 180 degrees, >> just as you would predict with VSEPR theory. Yet, the dipole moment is a >> robust 9.72 Debye, not 0 Debye as would be predicted by VSEPR theory. In >> addition, if you build carbon dioxide in 1.0.3 by selecting double bonds and >> turning off adjust hydrogens, the partial charge on the carbon and oxygen >> atoms remains zero, and not 0.37 for C and -0.19 for each O. Unfortunately, >> Ubuntu has not put the latest version of Avogadro in its repository. >> I cannot explain why such discrepancies exist in the software and so I'm >> calling on the users and developers of Avogadro for some help on explaining >> or overcoming such discrepancies. >> Thank you for your assistance, >> Steve >> >> -- >> Dr. Steven Petrovic >> Professor of Chemistry >> Southern Oregon University >> 1250 Siskiyou Blvd. >> Ashland, OR 97520 >> (541) 552-6803 >> >> ------------------------------------------------------------------------------ >> Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, >> MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current >> with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft >> MVPs and experts. SALE $99.99 this month only -- learn more at: >> http://p.sf.net/sfu/learnmore_122912 >> _______________________________________________ >> Avogadro-Discuss mailing list >> Avogadro-Discuss@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/avogadro-discuss >> > > ------------------------------------------------------------------------------ > Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, > MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current > with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft > MVPs and experts. SALE $99.99 this month only -- learn more at: > http://p.sf.net/sfu/learnmore_122412 > _______________________________________________ > Avogadro-Discuss mailing list > Avogadro-Discuss@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/avogadro-discuss ------------------------------------------------------------------------------ Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. SALE $99.99 this month only -- learn more at: http://p.sf.net/sfu/learnmore_122412 _______________________________________________ Avogadro-Discuss mailing list Avogadro-Discuss@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/avogadro-discuss
