Perturbation Theory

Perturbation Theory is a mathematical approach used to analyze complex systems by breaking them down into simpler parts. In the context of Hamiltonian and Matrix Mechanics, it helps us understand how a small change (or "perturbation") in a system's Hamiltonian (energy function) affects its behavior. Instead of solving the complex system directly, we start with a solvable case and then gradually add the small changes, calculating their influence on the system's properties. This technique is valuable in fields like quantum mechanics, where exact solutions are often difficult to find.