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The exact ground state energy of He is -79.0 eV. Using the variational method, you calculate an a...

The exact ground state energy of He is -79.0 eV. Using the variational method, you calculate an approximate energy to be -83.0 eV. You must have made an error because the variational method energies must

A. Equal the exact ground state energy

B. Be positive

C. (Equal or) lie above the ground state

D. (Equal or) lie below the ground state

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Answer #1

According to variational method E >= Eo as this is an approximate method and the wavefunction used is also approximate.

where Eo is the true ground state energy and E is the calculated energy

=> option c is correct.

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