Austin Method

A fairly recent reparameterization of AMI, called RM1 (for Recife, a city in Brazil where three of the four authors work by analogy with Austin method 1) is said to be better than AMI and PM3 and to be at least very competitive with PM5 (PM3, PM5 and PM6 see below) [64]. RM1 keeps the mathematical structure and qualities of AMI, while significantly improving its quantitative accuracy with the help of today s computers and also of the more advanced techniques available for nonlinear optimization. RM1 can be implemented in the AMI software without changing the code, other than altering the parameters. For 1,736 species considered in the parameterization some average errors were ... 

AMI Semiempirical Austin method 1 CSA Conformational space annealing DFT Density functional theory DFTB Density-functional-based tight binding EA Evolutionary algorithm... 

Naturally, group 4 elements are again the focus of interest. Structures of hydrocarbons (which maybe thought of as partly or completely passivated carbon clusters) have been optimized by Hobday and Smith [65]. Hydrogen-passivated silicon clusters have been studied a few times, for example by Chakraborti and coworkers [97,98] at the TB level, as well as by Ge and Head [99] at the semiem-pirical Austin method 1 (AMI) level, with DFT and MP2 refinement calculations they noted a marked influence of the passivation layer on cluster structures, with Si10H16 and Si14H20 already exhibiting bulk structure, in stark contrast to bare silicon clusters. 

The antioxidant efficiency of phenolic acids, as determined by the accelerated autooxidation of methyl linoleate and scavenging of the free radical 2,2-diphenyl-1-picrylhydrazyl (141) ° methods, was found to be inversely proportional to the maximal detector response potential in the voltammetric determination of these compounds. No similar correlation was found for the flavonoids . A good correlation was found between the O—H bond dissociation energy of a phenolic compound and its effectiveness as antioxidant, expressed as the rate constant of free radical scavenging . The bond dissociation energy of the phenol O—H bond was estimated by a three-dimensional quantitative structme-activity relationship method incorporating electron densities computed using the Austin Method 1 (AMI) followed by correlation of the... 

NDDO [20] goes beyond INDO in that the ZDO approximation (section 6.2.1, point (3)) is not applied to orbitals on the same atom, i.e. ZDO is used only for atomic orbitals on different atoms. NDDO is the basis of the currently popular semiempirical methods developed by Dewar and coworkers modified NDDO (MNDO), Austin method 1 (AMI) and parametric method (PM3). 

An alternative strategy was to develop methods wherein the two-electron integrals are parameterized to reproduce experimental heats of formation. As such, these are semi-empirical molecular orbital methods—they make use of experimental data. Beginning first with modified INDO (MINDO/1, MlNDO/2, and MINDO/3, early methods that are now little used), the methodological development moved on to modified neglect of diatomic differential overlap (MNDO). A second MNDO parameterization was created by Dewar and termed Austin method 1 (AMI), and finally, an "optimized" parametrization termed PM3 (for MNDO, parametric method 3) was formulated. These methods include very efficient and fairly accurate geometry optimization. The results they produce are in many respects comparable to low-level ab initio calculations (such as HF and STO-3G), but the calculations are much less expensive. 

Theoretical calculations (Austin Method 1, AMI) [40] carried out on the DCNQI molecule reveal that the LUMO energy of TCNQ is 0.4 eV lower than the... 

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