Oscillations in geo.opt.: Increase Basis Set starting from small BS

[Danylo]

Dear All,

during PBE/def2-TZVPP geometry optimization of a complex I have small oscillations that prevent convergence.
There are several possibilities to manage this problem:
1) optimize geometry with smaller basis set like def-SV(P) and afterwards increase basis set starting from def-SV(P) geometry (I did it and have oscillations for def2-TZVPP basis set);
2) distort the oscillated geometry little bit and start new optimization;
3) like 1, but additionally start from the def-SV(P) wavefunction and not from EHT. However, in this case, one has to add necessary math.functions and 0 coefficients in order to increase the wavefunction from def-SV(P) to def2-TZVPP.

Is it possible to do 3 in Turbomole?
Probably, you have other suggestions how to manage the problem of oscillations?

Thanks!

[Arnim]

Hi,

you can do 3 in define. If you do not type 'eht', but 'use <file>'. <file> is the path to the control file with the SV(P) MOs.
Then 'blowup' is carried out and the converged orbital are transformed to the new basis.

Cheers,

Arnim

[christof.haettig]

Two comments to this:

 *  in 'use <file>'  the <file> should be the name of a control (not mos!) file
 * whenever you change during a geometry optimization the basis set and/or the method,
    you should delete the files 'gradient' and 'energy', to prevent that the optimizer gets
    confused by the sudden change in the energy
Christof