Re: CCL:TDDFT on G03: negative transition energies

It should be noted that, in the TD-DFT framework (which is closely related
 to RPA), the response matrix cannot technically have negative eigenvalues.
 I would speculate that the eigenvalues reported by the code as negative are
 actually pure imaginary.  This does indicate an "instability" in the
 response matrix, which you could perhaps interpret as a lower-energy state.
 -Daniel
 On 6/2/05 1:09 PM, "S.I.Gorelsky" <gorelsky!at!stanford.edu>
 wrote:
 >
 >> I have done some B3lyp TDDFT calculations on some
 >> transition metal complexes and I have obtained some
 >> negative excitation energies . Does it make sense or
 >> it is an error of the code? Has anyone come across the
 >> same problem?
 >
 > This means that what you have got as a reference state in your calculation
 > is THE EXCITED STATE, and there is at least one lower-energy electronic
 > state (the TRUE ground state) at the given level of theory.
 >
 > Regards,
 >
 > S. Gorelsky
 >
 > ----------------------------------------------------------------
 >  Dr S.I. Gorelsky, Department of Chemistry, Stanford University
 >  Box 155, 333 Campus Drive, Stanford, CA 94305-5080 USA
 >  Phone: (650) 723-0041. Fax: (650) 723-0852.
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 --
 T. Daniel Crawford                           Department of Chemistry
 crawdad!at!vt.edu                                    Virginia Tech
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