Computational chemistry Hartree-Fock method

Each cell in the chart defines a model chemistry. The columns correspond to differcni theoretical methods and the rows to different basis sets. The level of correlation increases as you move to the right across any row, with the Hartree-Fock method jI the extreme left (including no correlation), and the Full Configuration Interaction method at the right (which fuUy accounts for electron correlation). In general, computational cost and accuracy increase as you move to the right as well. The relative costs of different model chemistries for various job types is discussed in... 

Bartlett RJ, Stanton JF (1994) Applications of post-hartree-fock methods a tutorial. In Lipkowitz KB Boyd DB (eds) Reviews in computational chemistry, vol. 5. Wiley-VCH, New York, pp 65—169... 

The various methods used in quantum chemistry make it possible to compute equilibrium intermolecular distances, to describe intermolecular forces and chemical reactions too. The usual way to calculate these properties is based on the independent particle model this is the Hartree-Fock method. The expansion of one-electron wave-functions (molecular orbitals) in practice requires technical work on computers. It was believed for years and years that ab initio computations will become a routine task even for large molecules. In spite of the enormous increase and development in computer technique, however, this expectation has not been fulfilled. The treatment of large, extended molecular systems still needs special theoretical background. In other words, some approximations should be used in the methods which describe the properties of molecules of large size and/or interacting systems. The further approximations are to be chosen carefully this caution is especially important when going beyond the HF level. The inclusion of the electron correlation in the calculations in a convenient way is still one of the most significant tasks of quantum chemistry. 

For quantum chemistry, first-row transition metal complexes are perhaps the most difficult systems to treat. First, complex open-shell states and spin couplings are much more difficult to deal with than closed-shell main group compounds. Second, the Hartree—Fock method, which underlies all accurate treatments in wavefunction-based theories, is a very poor starting point and is plagued by multiple instabilities that all represent different chemical resonance structures. On the other hand, density functional theory (DFT) often provides reasonably good structures and energies at an affordable computational cost. Properties, in particular magnetic properties, derived from DFT are often of somewhat more limited accuracy but are still useful for the interpretation of experimental data. 

Michel Dupuis, Proceedings of the Workshop on Recent Developments and Applications of Multi-Configuration Hartree-Fock Methods. Proceedings of a conference held at Texas A8cM University, July 15-17,1980, in National Resource for Computation in Chemistry Proceedings, No. 10, NTIS, Springfield, VA, 1981. 

R. J. Bartlett and J.F. Stanton, in K.B. Lipkowitz, D.B. Boyd (Eds.), Applications of post-Hartree-Fock methods A tutorial. Reviews in computational chemistry, Vol. V, VCH Publishers, New York, 1994, pp. 65-169. 

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