CCL: Interpretation of TDDFT results

 Sent to CCL by: Fedor Goumans [goumans,+,scm.com]
 Dear Radek,
Perhaps the Annual Reviews paper by Casida and Huix-Rotllant is instructive. Paragraph 2.2 describes excitations in a two-electron two-orbital system. 
 http://www.annualreviews.org/doi/abs/10.1146/annurev-physchem-032511-143803
 Best wishes,
 Fedor
 On 12/23/2013 8:31 AM, Radoslaw Kaminski rkaminski.rk*|*gmail.com wrote:
 
 Sent to CCL by: "Radoslaw  Kaminski" [rkaminski.rk]*[gmail.com]
 Dear All,
 I would like to ask a question regarding the practical interpretation of TDDFT
 results. When I do the TDDFT calculation I get a set of computed transitions,
 allowed and forbidden (e.g. S0 state -> T1 state). Later, in the output of
 various programs, there are shown as mixtures of some 'orbital transitions',
 with some coefficients. For example ADF prints out:
       9: 405a       -> 408a          0.9449
       9: 406a       -> 409a          0.0464
       9: 400a       -> 407a          0.0038
       9: 401a       -> 407a          0.0027
       9: 405a       -> 409a          0.0002
 I was looking for a nice literature or tutorials how to practically interpret
 such results, unfortunately with no significant results. The thing I am a bit
 puzzled with is the relation of such 'mixed' transitions to the one-determinant
 approximation, which is used in the practical implementation of the DFT method.
 The S0 state has no unpaired electrons, T1 has two: one electron on former HOMO
 (now SOMO), and the other one on former LUMO (now other SOMO), and other excited
 configurations can be expressed in a similar way. Why then some of the computed
 transitions engage many orbitals with various contributions? What does it mean?
 Some nice tutorials or literature would be of a very much advantage for me.
 Thanks in advance.
 Best wishes,
 Radek>
 
 --
 Dr. T. P. M. (Fedor) Goumans
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 Scientific Computing & Modelling NV (SCM)
 Vrije Universiteit, FEW, Theoretical Chemistry
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