1. Last hour:
Variation Theorem in QM: If a system has the ground state energy E0 and the Hamiltonian ,then for any normalizeable WF  we have
We can use any trial WF  that satisfies the boundary conditions of the system, so  can contain adjustable parameters.
Approach requires no knowledge of real solution except boundary conditions.
Variation method yields upper limit on ground state energy of a system, quality of approximation depends on trial wave function .

2. Learning Goals for Chapter 17 – Variation Theory
After this chapter, the related homework problems, and reading the relevant parts of the textbook, you should be able to:
apply the variation method to obtain approximation to ground state energy for a given Hamiltonian and trial function with adjustable parameters;
choose a suitable trial function for a given Hamiltonian;
qualitatively explain a strategy for computational application of variation theory
explain the limitations of variation approaches.