Hi!

As far as I know, there are no recommendable basis sets with ECPs for 3d transition metals.

And what do you expect that you can save with an ECP here? When you put a Ne core in an ECP, you might only make the cheap HF reference wave funtion calculation a bit faster (if at all). In the following expensive CCSD(T) calculation, you would exclude the Ne core anyways using the frozen core approximation. Therefore, using a ECP here is not necessarily the way to go.

Cheers,

Arnim

Hi!

Thanks for your answer, you are completely right.

However I found the bottle neck for my problem:

I was trying to reduce the time cost by increasing the nodes used to calculate it, but the efficient change has been to increase the RAM associated with the mentioned calculus.

Lluís