The Schrodinger equation reads $$ \begin{equation} \hat{H}(x_1, x_2, \dots , x_A) \Psi_{\lambda}(x_1, x_2, \dots , x_A) = E_\lambda \Psi_\lambda(x_1, x_2, \dots , x_A), \tag{1} \end{equation} $$ where the vector \( x_i \) represents the coordinates (spatial, spin and isospin) of particle \( i \), \( \lambda \) stands for all the quantum numbers needed to classify a given \( A \)-particle state and \( \Psi_{\lambda} \) is the pertaining eigenfunction. Throughout this course, \( \Psi \) refers to the exact eigenfunction, unless otherwise stated.