OVGF method semiempirical

It was shown previously in a series of papers " that the OVGF method, developed by the Cederbaum group,can be coupled to NDDO-based semiempirical molecular orbital... 

We have used the outer valence Green s function (OVGF) method coupled with semiempirical approximations to calculate the IPs of a variety of molecules ranging from benzene to fullerenes. We also extended the method to calculate IPs... 

In this article, we summarize the results of our previous OVGF calculations based on the commonly used semiempiri-cal methods (modified neglect of diatomic overlap, MNDO Austin Model 1, AMI and parametric methods, PM3 ) and compare them with the results of the recent semiempirical ab initio method 1 (SAMl) and MNDO/d " semiempirical methods. The focus is on methodology of the method and its performance. 

The SAMI method gives a little better agreement with experimental data (A = 0.41 eV for 22 anions) than the other KT-based semiempirical methods, but improvement over the AMI method is not so considerable (A = 0.50 eV). It should be especially noted that poor agreement between SAMI calculated values and experimental data was obtained for the pentachlorobenzenide (Table 8, entry 5) and trimethylsilanide (entry 10) anions, with a discrepancy of about 1.5 eV. The OVGF(AMI) values are in considerably better accord with experiment in comparison with the results of KT-based. semiempirical calculations. This becomes apparent from the mean deviation data in Table 8. The A value is reduced by about twofold in the OVGF(AMl) calculations and is only 0.25 eV. The importance of electron correlation and orbital relaxation... 

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