I know to describe Quantum Mechanical systems we can use: -Schrodinger equation -Feynman Path Integral method -Heisenberg Matrix formulation Well my question is, if you want to calculate molecular properties, and want to understand biochemistry (protein), you have a system with several quantum particles right?. What would be the best method to do this calculations? What is commonly used in Quantum Chemistry and Biochemistry? Obviously I guess there are not analytical solutions to most problems so you need to use numerical methods. Is anybody familiar with Quantum Chemistry? THanks!