This lecture covers topics such as boundary conditions, the Crank-Nicolson scheme, the Heisenberg uncertainty principle, Fourier transforms, the harmonic oscillator, semi-classical states, potential barriers, resonances, and stationary Schrödinger equation. It also discusses the probabilistic interpretation, energy conservation, free particles, wave packet spread, and the effects of dispersion. Demonstrations and formal mathematical proofs are presented, emphasizing the importance of harmonic oscillators and energy states in quantum physics.