Parameterization general-purpose

Three versions of Modified Intermediate Neglect of Differential Overlap (MINDO) models exist, MINDO/1, MINDO/2 and MINDO/3. The first two attempts at parameterizing INDO gave quite poor results, but MINDO/3, introduced in 1975, produced the first general purpose quantum chemical method which could successfully... 

MOPAC is a general-purpose semiempirical molecular orbital program for the study of chemical structures and reactions. It is available in desktop PC running Windows, Macintosh OS, and Unix-based workstation versions. It uses semiempirical quantum mechanical methods that are based on Hartree-Fock (HF) theory with some parameterized functions and empirically determined parameters replacing some sections of the complete HF treatment. The approximations in... 

It is a general-purpose program that is carefully parameterized for a wide variety of molecular types. 

AMI and PM3 perform similarly and usually give quite good geometries, but less satisfactory heats of formation and relative energies. A modification of AMI called SAMI (semi-ab initio method 1), relatively little-used, is said to be an improvement over AMI. AMI and SAMI represent work by the group of M. J. S. Dewar. PM3 is a version of AMI, by J. J. P. Stewart, differing mainly in a more automatic approach to parameterization. Recent extensions of AMI (RM1) and PM3 (PM6) seem to represent substantial improvements and are likely to be the standard general-purpose semiempirical methods in the near future. 

The Zerner s INDO method (ZINDO) is also called spectroscopic INDO (INDO/S). This is a reparameterization of the INDO method specihcally for the purpose of reproducing electronic spectra results. This method has been found to be useful for predicting electronic spectra. ZINDO is also used for modeling transition metal systems since it is one of the few methods parameterized for metals. It predicts UV transitions well, with the exception of metals with unpaired electrons. However, its use is generally limited to the type of results for which it was parameterized. ZINDO often gives poor results when used for geometry optimization. 

Once you realize that attributes do not directly represent stored information, the unconventional concept of a parameterized attribute is a natural extension. A parameterized attribute is one that has a defined value for each of many different possible values of its parameter(s). Like attributes generally, it is best thought of as a query, or read-only, function that has been hypothesized for some purpose it need not be directly implemented. 

That said above does not mean that a semiempirical parameterization based on the HFR MO LCAO scheme and valid for a certain narrow class of compounds or even for a specific purpose cannot be built. It is done for example in [69] for iron(H) porphyrins. But in a more general case there is no way to arrive to any definite conclusion [76] about the validity of a semiempirical parameterization in the HFR context. On the other hand we have to mention that the semiempirical method ZINDO/1 [77] which allows for... 

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