SEARCH Articles Figures Tables Anharmonic coupling theory adiabatic approximation Approximate Equations of the Adiabatic Theory Approximate Molecular Orbital Theory for 4-Electron 3-Centre Bonding Units Approximation canonical transformation theory Approximations in Relativistic Density Functional Theory Approximations of MO theory Approximations of MO theory Born-Oppenheimer Approximations of MO theory Hartree-Fock Approximations of MO theory Wolfsberg-Helmholtz Approximations of MO theory independent electron Approximations of MO theory nonrelativistic Approximations of MO theory zero-overlap Approximations to Exact Perturbation and Response Theory Expressions Born-Oppenheimer approximation time-dependent molecular theory Born-Oppenheimer approximation transition state theory Brillouin-Wigner perturbation theory approximation Coherent potential approximation theory Computational quantum mechanics approximate orbital theories Contact approximation integral encounter theory Coupled Cluster Doubles theory, linear approximation Coupled-cluster theory approximate methods Coupled-cluster theory approximate triples treatment Density functional theory Kohn-Sham approximation Density functional theory approximate treatment Density functional theory approximations Density functional theory generalized gradient approximation Density functional theory generalized random phase approximation Diffusion theory Gaussian approximation Effective medium approximation theories Electron propagator theory approximations Flory-Huggins theory mean-field approximation Hartree-Fock theory approximation Hiickel theory, extended approximations Hypemetted chain approximation approximate theories Information theory approximations Integral approximation, semiempirical molecular orbital theory Integral equation theories closure approximation Interaction site fluids approximate theories Liquids approximate theories Lubrication approximation theory MNDO approximation, semiempirical molecular orbital theory Many-Body Perturbation Theory and the GW Approximation Mean spherical approximation pairing theories Mean-field approximations theory Mean-spherical approximation theory Method approximate density functional theory Molecular orbital theory Hartree-Fock self-consistent field approximation Molecular orbital theory approximate Molecular orbital theory approximate methods Molecular orbital theory approximation Molecular orbital theory tight-binding approximation Numerical Results and Approximate Theories Optimal control theory approximation Orbital approximate theories Perturbation and Response Theory with Approximate Wavefunctions Perturbation theories approximation Perturbation theory high-temperature approximation Perturbation theory. A comparison with results obtained in the Heitler-London approximation Picture change effects in approximate relativistic theories Rayleigh-Schrodinger perturbation theory approximation Second-order perturbation theory approximate Self consistent field theory approximation Simple Hiickel molecular orbital theory approximations Spin coupling constants approximate theory Statistical mechanics approximate theories Stochastic theory approximation Sudden approximation theory Superposition approximation theories, exact solutions Theories linear driving force approximation Third approximation of Flory-Huggins theory Thomas-Fermi theory approximations Transport processes approximate theories Valence bond, approximation theory