At first thanks for the references Gregorio!! :) Some of them I really dont know until now!
The question I alwaus rise on this issue is that, sure, the electronic density derived from the Kohn-Sham orbitals do have the information about all electronic states for a given system in a given external potential. But, as most refereces you already cited above, to extract this information it is necessary to go beyond the time-independet approach. And that is were the discussion comes back to the caqhero question. There might be particular TD siesta implementations ... but they are particular! Concerning on the relation between IPs/EAs and HOMO/LUMO ... sure, you are absolutely right. But this LUMO just assumes a physical meaning if you are putting one electron there and calculating the EA. Otherwise, this orbital will never be taken into account while minimizing the electronic energy. Caqhero To be brief ... the official SIESTA package is not an implementation of Time-Dependent DFT. :( Cheers NH 2011/3/4 Gregorio García Moreno <[email protected]> > There is some controversia about the physics meaning of Kohn-Sham > ortibals, i.e. Koopman's theorem is no sastified. However, Perdew, using > Janak’s theorem has proven a connection between IPs / EAs and HOMO / LUMO > energies, respectively > P. Perdew, in: R.M. Dreizler, J. Providenca (Eds.), Density Functional Methods > in Physics, Plenum Press, New York and London, 1985, > > E. Jansson, P. C. Jha, H. Ågren, Chem. Phys. 330, 166, 2006.). > > Furthermore, it is known that long-range corrected functionals give > accurate orbital energies and satisfy Koopman theorem. > > > Tsuneda, T.; Song, J. W.; Suzuki, S.; Hirao, K. J. Chem. Phys., 2010, 133, > 174101. ** > > Rienstra-Kiracofe, J. C.; Tschumper, G. S.; Schaefer, H. F.; Nandi, S.; > Ellison, G. B. Chem. Rev. 2002, 102, 231-282. > > Jacquemin, D.; Adamo, Carlo, J. Chem. Theory Comput, 2011, 7, 369-376. > > JacJCTC08. D. Jacquemin, E. A. Perpète, G. E. Scuseria, I. Ciofini, C. > Adamo, J. Chem. Theory Comput., 2008, 4, 123.WonJCTC10. b. > > Wong, T. H. Hsieh, J. Chem. Theory. Comput, 2010, 6, 3704.JacJCP07. D. > Jacquemin, E. A. Perpète, G. Scalmani, M. J. Frisch, R. Kobayashi, > > C. Adamo, J. Chem. Phys., 2007, 126, 144101. > > Y. Tawada, T. Tsuneda, S. Yanagisawa, T. Yanai, and K. Hirao, “A > long-range-corrected time-dependent density functional theory,” *J. Chem. > Phys.*, *120* (2004) 8425. > > Sorry, perhaps we are moving away from the Caqhero's problem > > > El 3/4/2011 11:08 AM, N H escribió: > > Well ... for sure there are lots of studies using DFT to calculate such > properties. Another question is whether this results are meaningful or > not... and that is controversial. > > The problem is that some people don´t see much meaning on conduction bands > calculated with single reference methods, since their eigenvalues are not > really taken into account while diagonalizing the system's Hamiltonian. > > Another issue is the meaning of the Kohn-Sham orbitals themselves. It has > been demonstrated - at least for molecules - that they do have the same > simmetry properties as HF orbitals and that the also agree with the > Koopman's theorem after rescalling. I also know that there are some recent > works (see the link) on a DFT version of the Koopman's theorem, but in order > to verify that you have to go beyond standard DFT: > > > http://www.ingentaconnect.com/content/nrc/cjc/2009/00000087/00000010/art00014 > > > Given that, you can calculate the optical properties of any material with > DFT if you think that the conduction bands are meaningful ... but you are > going to have a hard time if your referee think it is not true. > > Cheers > > NH > > 2011/3/4 Gregorio García Moreno <[email protected]> > >> Hi >> I have never used SIESTA to calculate optical properties, but recently >> have accepted a propious work where electronic structure of conducting >> polymers: band diagrams, bandgap, bandwiths, effective mass, ect. All these >> properties are related with optical properties, and the reviewers didn't say >> anything about the methodology (DFT and SIESTA) >> I can't help you, but you can look for other works where DFT implemented >> in siesta is used to assess optical properties. >> Besides, respect to DFT there are a lot of works which use DFT to >> calculate optical properties of photovoltaic cells, oleds, synthetized dyes, >> etc. >> I think that that all works of nowadays on optical properties use DFT. >> I know that Carlo Adamo's group are working in the development of new >> fuctionals to assess optical properties. >> Unfortunately, all these functional are not implemented in SIESTA. >> On the other hand, there are a lot of scale factors in bibliography to >> correct theoretical values in concordance with experimental ones. >> >> Sorry, I can't help more >> >> Gregorio >> >> El 3/4/2011 9:16 AM, caqhero escribió: >> >> Recently, I used the siesta to calculate the optical properties of CNTs. >> The reviewer ask the method I used. and he say that the Ground-state DFT can >> not accurately describe optical properties. I confuse the method for optical >> calculation in siesta. can any body tell me the details ? how can I reply >> the reviewer ? is it reliable using the siesta to calculate the optical >> properties ? any suggestion is appreciated ! thank you ! >> >> >> >> >> >
