Configuration Interaction: Excited State Configurations

This lecture covers the concept of Configuration Interaction (CI), where excited state configurations are generated from the ground state Hartree-Fock wavefunction. It explains the creation of single and double excitations, the use of Slater determinants, and the full CI method for exact results. The lecture also discusses CIS, CISD, and other methods to capture correlation effects, as well as the variational theorem for finding the best wavefunction. The application of multireference CI (MRCI) for static correlation effects and the matrix diagonalization process to solve the many-electron Schrodinger equation are also explained, along with the Slater-Condon rules for determining Hamiltonian matrix elements.