Quantum-chemical methods for the construction of wave functions of many-electron systems alternative to the Hartree-Fock approximation

Modern quantum-chemical methods for the construction of approximate many-electron wave functions differing from the traditional Hartree-Fock approximation are considered. Attention is focused on the methods based on the use of symmetric groups and nodal surfaces of many-electron wave functions. A new interpretation of the Pauli exclusion principle is discussed.