TURBOMOLE Users Forum
TURBOMOLE Modules => Relax => Topic started by: ghill on May 22, 2007, 01:29:47 PM

I'm trying to optimize an RIMP2 fitting basis with cbasopt and I'm running into problems with one or more exponents of the same l quantum number becoming very similar.
Is this just a sign that I need to create larger spaces between consecutive exponents or is it more a suggestion that I should be considering more or less functions in my basis set?
One thing that I have noticed is that the HF energy for the system is always reported as zero. Might this be an indication of a problem in my input or the way I'm attempting to run the optimization?
Any tips or advice on using cbasopt would be greatly appreciated.

Hi,
1) the HF energy is not used in the optimization of the auxiliary basis functions
for RIMP2/RICC2. At some point of the basis set optimization it is overwritten
by something else. Relax needs the functional which should be minimized
and its gradient.
2) coalescence of parameters is a very common problem in nonlinear
optimization/fitting... the reasons can be very different:
* redundant exponents
* missing tighter or diffuser exponents
* missing exponents of higher or lower angular momentum
Christof

Thanks for the advice.