Author Topic: Perrhenate, ECP, B3LYP  (Read 3308 times)

wilhelm

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Perrhenate, ECP, B3LYP
« on: March 18, 2011, 11:04:35 am »
Hi,

I don't know if this is the right section, it might also fit into 'define'.

I would like to calculate certain perrhenates starting with the simple perrhenate anion ReO4-. To produces energies comparable to a certain publication, I would like to use 6-311G(d,p) for oxygen and a lanl2dz ECP for rhenium. As I had troubles defining the lanl2dz ECP in define, I used def2-TZVP/def2-ecp for Re, 6-311G-pol for O and ri.

The input struture has been optimized with a different QM code to be sure to have a good input. It is basically a tetrahedral geometry as expected. When I run a geometry optimization, the geometry gets planar and the bond lengths become very short. I also have to restart the calculation, as it stops due to convergence errors.

Can someone give me a hint?

Thanks,

Wilhelm

Arnim

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Re: Perrhenate, ECP, B3LYP
« Reply #1 on: April 26, 2011, 04:23:13 pm »
Hi!

Do you really use 6-311G-pol? That would be just the polarization function of 6-311G*.
When you are using only 1 d-function on the oxygen, it wouldn't be a big surprise to run into convergence problems.

Cheers,

Arnim