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Alex Granovsky
gran@classic.chem.msu.su

as to XMCQDPT, the input file is pretty much the same as for MCQDPT
calculations, the only difference is that instead of $mcqdpt input
group you need to use the $xmcqdpt one. All the keywords of these
two input groups are the same, and have the same meaning.

As to real calculations, you need to select the proper active space first,
then perform CASSCF calculation to get converged CASSCF orbitals.
Check that the orbitals are indeed the ones you have expected,
then use them as starting orbitals for xmcqdpt run. You may need
rather large dimension of the effective Hamiltonian (e.g., 10x10)
to get the energies of the lowest transitions converged.

regards,
Alex Granovsky

On Sat Apr 17 '10 10:02pm, Alexandr wrote
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>On Sat Apr 17 '10 9:56pm, Alexandr wrote
>----------------------------------------
>>Dear Alex,
>>And experts FireFly!

>>I study methods spectrophotometry diluted (10-5 _10-6 M) water solutions of various acidity of organic substances of a class trioxyfluorone (TOF). I should establish an order dissociation protons of three hydroxyl groups TOF. For calculation of frequencies in an electronic spectrum used TDDFT. I wish to calculate sets of frequencies for all variants dissociation TOF. At once there was a problem. I have received a spectrum of absorption of solution TOF in the known form for it in water. In attached files (Doc1 - Doc 3) comparison of this spectrum of a solution of particle TOF (a red line) to the calculated frequencies is resulted. In vacuum (Doc 1 for comparison) with hybrid functional B3LYP artefacts of frequencies are found out at 639 and 1427 nanometers (it is natural). To get rid of artefacts I used method PCM with the same hybrid functional B3LYP (Doc 2) and with a functional with the increased weight HF of exchange - BHHLYP (Doc 3). As a result I had a suspicion that among existing set of functionals always will be such which by the criteria accepted by us will allow to describe well to (explain) any experimental data?. But after all it is elementary adjustment to the given connection. And it is necessary to me, that the method could predict at least frequency of the first long-wave transition of other variants of ions TOF. For example, for considered particle TOF there are three variants dissiciation, for 2-charg an ion - two or three variants and so on are possible. The geometry of these of structure is already optimised by me.
>>   Very much I ask you of the help. As to me to change mine a Input file (Doc 4) to solve a problem. Or: what method should be used for this purpose? So, I have found A.Granovskogo's presentation of method XMCQDPT2 from 10.12.2008. However in respect of practical use of this method - in the Internet there is a full fog.
>>
>> Best regards,
>>  Alexandr.
>>