Quantum chemistry Chemistry 18 Molecules 10 Quantum theory 6 Chemical bonds 5 Molecular orbitals 5 Molecular structure 5 Chemistry, Physical and theoretical 4 Crystallography 4 Physical chemistry 4 Quantum mechanics 4 Atoms 3 Computational chemistry 2 Density functionals 2 Hydrogen atom 2 Many-body problem 2 Mathematics 2 Molecular dynamics 2 Molecular spectroscopy 2 Organic chemistry 2 Quantum field theory 2 Spectroscopy 2 Spectrum analysis 2 Wave mechanics 2 Analytical chemistry 1 Angular momenta 1 Angular momentum 1 Approximate methods 1 Atomic spectra 1 Biological chemistry 1