Question

What is the largest atom with a reliable configuration-interaction (CI) calculation?

Answer 1

The simplest approximation for calculating the ground state of an atom is the Hartree-Fock approximation.

To get accurate result for the ground state energy, one has to do configuration-interaction (CI). But then the dimension of the Hilbert space is huge.

So, so far, which atom is the largest one with a reliable CI calculation

Answer 2

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Do configuration-interaction (CI). But then the dimension of the Hilbert space is huge.


Configuration Interaction (CI) calculations on the ground state of the C-atom are carried out using.

The CISD excitation energies for water are known to be too large compared 

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