CCL:G: ri-dft (bp86/def-SVP) calculations for Mn(V) oxo porphyrin dimer

 Sent to CCL by: Uwe Huniar [uwe.huniar . cosmologic.de]
 Hello,
 the SCF convergence in Turbomole can be controlled by:
 1. the maximum number of SCF iterations ($scfiterlimit)
 2. using a higher DIIS damping  ($scfdamp), I would recommend to start with a
 damping factor between 4 to 8. If that does not help, try:
   2.a) set the damping factor to a high value like 15, and limit the number of
        SCF iterations to, say, 20.
   2.b) after that, reduce the damping factor to something like 4 and continue
        with $scfiterlimit of 300 (or so).
   You can check the convergence graphically (if gnuplot is installed) by calling
        cgnce <output-filename>
   and if the energy starts to oscillate, the damping factor is too high...
 3. using another orbital shift ($scforbitalshift)
 All other procedures might alter your occupation, and that is something you do
 not want to have in your case.
 There is a short chapter (6.9) about SCF convergence also in the Tutorial of
 TURBOMOLE, which can be found in the DOC directory of your Turbomole
 installation. A detailed description of the keywords can be found in the
 documentation.
 Yours,
 Uwe
 > I am doing some ri-dft (bp86/def-SVP) calculations for Mn(V) oxo porphyrin
 > dimer system(s) with TURBOMOLE 5.9.0
 >
 > I managed to optimize the ferromagnatically (F) coupled nonet spin state (F
 > copled quintets of the individual Mn sites) for the above system. Then I
 > tried to optimize the anti-ferromagnatically coupled singlet (AF copled
 > quintets of the individual Mn sites) using the orbitals, geometry of the F
 > coupled nonet and assigning the exact electron occupancy. But SCF
 convergence
 > for the AF singlet was not succeeded. After that, I followed the same
 > procedure with dft (b3-lyp/def-SVP), but it did not work.
 >
 > According to my previous calculations with GAUSSIAN 03 for the same
 > system(s), AF coupled electronic configurations are quite important than F
 > coupled spin states. But G03 calculations are time consuming. If I would
 > manage to optimize the AF coupled spin states using ri-dft, I can save my
 > time.
 >
 > Any comments would be appreciated.
 >
 >
 > W. M. C. Sameera (PhD student)