Re: CCL:absorbance spectra or colored compound prediction

 2005 June 145
 Hello,
 "DFT-theory only gives something physically
 meaningful and interpretable for the overall-electron density (and all
 quantities derivable from that), but not for "single
 electron"-wavefunctions
 (=MOs)."
Regarding physical interpretations of the Kohn-Sham orbitals: correlations between Kohn-Sham and conventional (ab initio and by implication semiempirical) MOs have been found: 
 1) R. Stowasser, R. Hoffmann, JACS, 1999, _121_, 3414
 2) E. J. Baerends, Theoretical Chemistry Accounts, 2000, _103_, 265.
 3) D-P Chong et al., J Phys Chem A, J Chem Phys, 2002, _116_, 1760.
 4) C-G Zhan et al., J Phys Chem A, 2003, _107_, 4184.
 See too:
 a) H. M. Muchall et al., Can J Chem, 1998, _76_, 221
 b) J. Fabian et al.,  J Mlec Modelling, 2000, _6_, 177.
 c) T. Kar et al., J Phys Chem A, 2000, _104_, 9953.
 EL
 ====
 Andreas Serr wrote:
 
 Dear all,
 S. I. Gorelsky and A. B. P. Lever used ZINDO and TD-DFT a lot for calculating
 absorption spectra of (charged) transition metal complexes. There are numerous
 papers where they used both techniques, but this one might be a good start:
 J Organomet Chem, 635 (2001) 187-196.
 The conclusions are that both methods yield similar results, most interestingly,
 that this also applies to the calculated MOs (Kohn-Sham-orbitals vs.
 semiempirical ZINDO/s-MOs). I do not know too much about DFT/TD-DFT, but to my
 knowledge prior to that publication, DFT-theory only gives something physically
 meaningful and interpretable for the overall-electron density (and all
 quantities derivable from that), but not for "single
 electron"-wavefunctions
 (=MOs). However, I might be wrong.
 Best wishes,
 Andreas
 Geoff Hutchison wrote:
 
 On Jun 13, 2005, at 2:07 AM, Rey Puiggros Oscar wrote:
depending on the size of your system my choice would be Time Dependent Density Functional Methods or ZINDO/S. The first one is quite accurate but it is more expensive, while ZINDO/S is semi- empirical and faster but with lower accuracy.
I'm not sure I'd completely agree with that. For neutral organic molecules, I think ZINDO/S does almost as well as TDDFT. Both do well with low-lying excited states. 
 e.g.
 Hutchison, G. R.; et. al. J. Phys. Chem. A 2002, 106, 10596.
 Fabian, J. Theor. Chem. Acc. 2001, 106, 199.
I'm sure there are similar "benchmark" studies too. (Although if anyone has similar comparative experiment vs. computed papers for charged organic species, I'd be grateful for references.) 
 -Geoff