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
