Dear Emilio, Thanks for your reply. I understand that Mulliken analysis is very sensitive to the basis set. However, I would not have expected the use of any valid basis set to effectively result in the reversal of the polarity of the bond. Or perhaps I am interpreting the results incorrectly?
With regards to the basis set etc., I am using the example input file and pseudopotentials supplied with Siesta. This file uses the default double zeta plus polarization basis set. Regards, Ben -----Original Message----- From: Siesta, Self-Consistent DFT LCAO program, http://www.uam.es/siesta [mailto:[EMAIL PROTECTED] On Behalf Of Emilio Artacho Sent: 14 July 2005 12:56 To: [email protected] Subject: Re: [SIESTA-L] Dear Benjamin Without enetering the details of your calculations, the Mulliken analysis gives numbers that can be very sensitive to the basis set used. Emilio Benjamin Rogers wrote: > Dear All, > > > > I am attempting to perform Mulliken analysis on some molecular > systems, however I am becoming confused by the output of Siesta. As > an example, consider the Mulliken output from the calculation of water > using the pseudopotentials and input file provided in the examples > folder. This indicates a valence charge on the oxygen of 5.717 and a > valence charge on each hydrogen of 1.142. This seems to disagree with > conventional thought of the oxygen atom having a high > electronegativity, which would result in it having a valence charge > above 6 in water. > > > >In addition, Mulliken analysis from GAMESS given at http://www.chem.swin.edu.au/modules/mod5/annot_h2o_g.html indicates a charge on oxygen of 8.274 (a valence charge of 6.274) and a charge on hydrogen of 0.863. This appears to conform to the conventional description of water, and is therefore as expected. > > > >Can anyone please explain the Siesta results? > > > >Thank you in advance, > > > >Ben. > > > > > > > This message has been checked for viruses but the contents of an > attachment may still contain software viruses, which could damage your > computer system: you are advised to perform your own checks. Email > communications with the University of Nottingham may be monitored as > permitted by UK legislation. > -- Emilio Artacho Department of Earth Sciences, University of Cambridge Downing Street, Cambridge CB2 3EQ, UK Tel. (+44/0) 1223 333480, Fax (+44/0) 1223 333450 [EMAIL PROTECTED], http://www.esc.cam.ac.uk/~emilio This message has been checked for viruses but the contents of an attachment may still contain software viruses, which could damage your computer system: you are advised to perform your own checks. Email communications with the University of Nottingham may be monitored as permitted by UK legislation.
