Re: CASPT2 convergence

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Posted by Roser on January 14, 2015 at 09:35:40:

In Reply to: Re: CASPT2 convergence posted by Steven Vancoillie on January 13, 2015 at 11:06:27:

Can I compare results of two compounds, one obtained using the shift but the other without it?
I will do rassi and single aniso calculations before the caspt2. And I want to compare two compounds (Dy and Er complexes).
The caspt2 calculations of Dy(III) complex converged without shift, but for Er complex I must use shift.
I wanted to observe if the shift gives different results for the same compound. I repeated the caspt2 for Dy complex with shift=0.4. Results differ in energies, g-tensors... Then I think I can't compare results.
Are convergence problems due to intruder states? Why a caspt2 calculation may not converge?
Thank you


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