TURBOMOLE Modules > Relax
Fitting functions coalesce in cbasopt
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ghill:
I'm trying to optimize an RI-MP2 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.
christof.haettig:
Hi,
1) the HF energy is not used in the optimization of the auxiliary basis functions
for RI-MP2/RI-CC2. 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 non-linear
optimization/fitting... the reasons can be very different:
* redundant exponents
* missing tighter or diffuser exponents
* missing exponents of higher or lower angular momentum
Christof
ghill:
Thanks for the advice.
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