Need some help with simulating molecules with VQE

Question

I have studied the example of the simulation of LiH molecule in Learning Quantum Computation using Qiskit. It is available on this link: https://qiskit.org/textbook/ch-applications/vqe-molecules.html#VQE-Implementation-in-Qiskit .
I don't understand the following cell:
Why freeze_list and remove_list are initialized in this way?
How does this procedure work?

KAJ226 · Answer

The freeze list indicates frozen of the core orbital. If you execute: molecule.core_orbitals you will get the output: [0]. So that is why the freeze list initialize that way.
As for the other two orbitals, [-3,-2] in the remove_list, this have to do with some chemistry intuition or calculation to determine that it has no effect to the overall problem. Thus they can be removed without any consequences to the answer. This will save us to have to use additional qubits.

Need some help with simulating molecules with VQE

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