We now see that the requirement that the total eigenfunction isantisymmetric with respect to the exchange of the labels of the twoelectrons effectively leads to a coupling between their spin andspatial coordinates. The electrons act as if they move under aforce whose sign depends on the relative orientation of theirspins.

This section is the bonus section for question 1. Consider thehelium atom which is a two- electron atom as we have discussedabove. The ground state is

1s2.

(k) Referring to your list of the s and t total eigenfunctions,write the ground state wave

function for He. Why is this one the only wave function for theground state?

We will now consider the Coulomb electron repulsion in ourtwo-electron atom. You are certainly not expected to do a detailedperturbation theory calculation.

(l)However,justarguingfromyourqualitativeknowledgeofthesandtstates,whichdoyou expect, in general cases other than the ground state, to havethe lower energy and why?

We now see that the requirement that the total eigenfunction isantisymmetric with respect to the exchange of the labels of the twoelectrons effectively leads to a coupling between their spin andspatial coordinates. The electrons act as if they move under aforce whose sign depends on the relative orientation of theirspins.

This section is the bonus section for question 1. Consider thehelium atom which is a two- electron atom as we have discussedabove. The ground state is

1s2.

(k) Referring to your list of the s and t total eigenfunctions,write the ground state wave

function for He. Why is this one the only wave function for theground state?

We will now consider the Coulomb electron repulsion in ourtwo-electron atom. You are certainly not expected to do a detailedperturbation theory calculation.

(l)However,justarguingfromyourqualitativeknowledgeofthesandtstates,whichdoyou expect, in general cases other than the ground state, to havethe lower energy and why?