<Table> <Tr> <Th> Electronic structure methods </Th> </Tr> <Tr> <Th> Valence bond theory </Th> </Tr> <Tr> <Td> Generalized valence bond Modern valence bond Resonance </Td> </Tr> <Tr> <Th> Molecular orbital theory </Th> </Tr> <Tr> <Td> Hartree--Fock method Semi-empirical quantum chemistry methods Møller--Plesset perturbation theory Configuration interaction Coupled cluster Multi-configurational self - consistent field Quantum chemistry composite methods Quantum Monte Carlo Linear combination of atomic orbitals </Td> </Tr> <Tr> <Th> Electronic band structure </Th> </Tr> <Tr> <Td> Nearly free electron model Tight binding Muffin - tin approximation Density functional theory k p perturbation theory Empty lattice approximation </Td> </Tr> <Tr> <Td> Book </Td> </Tr> <Tr> <Td> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> </Td> </Tr> </Table> <Tr> <Th> Electronic structure methods </Th> </Tr> <Tr> <Th> Valence bond theory </Th> </Tr>

Describe the ground state of oxygen molecule in valence bond terms