Austin Model 1 Hamiltonian

The AMI (Austin Model 1) Hamiltonian available in Version 3.10 of the MOP AC (Molecular Orbital PACkage) program was used to carry out QM calculations, for the purpose of estimating the partial atomic charges to be used in the electrostatic portion of the potential energy for the calculations on the interactions between pairs of model molecules. [34] The AMI calculations also yielded quantum mechanical estimates of the heats of formation of the model molecules. These heats of formation generally followed similar trends to the MM2 steric energies. 

The systems discussed in this chapter give some examples using different theoretical models for the interpretation of, primarily, UPS valence band data, both for pristine and doped systems as well as for the initial stages of interface formation between metals and conjugated systems. Among the various methods used in the examples are the following semiempirical Hartree-Fock methods such as the Modified Neglect of Diatomic Overlap (MNDO) [31, 32) and Austin Model 1 (AMI) [33] the non-empirical Valence Effective Hamiltonian (VEH) pseudopotential method [3, 34J and ab initio Hartree-Fock techniques. 

Several workers (Von Oepen et al., 1991 Reddy and Locke, 1994 Dai et al., 1999 2000) have utilized quantum chemical descriptors to model soil sorption. Dai et al. (2000) found a good QSAR for a series of benzaldehydes, using the Austin Model 1 (AMI) Hamiltonian ... 

AMI Austin Model 1. A semi-empirical quantum chemical Hamiltonian originating from the M.J.S. Dewar group. The quality of the AMI results in many cases is beyond the simpler ab initio results and is superior to the MNDO... 

In a joint experimental and theoretical publication [1057], the results of nuclear magnetic resonance (NMR) measurements performed on polyisothianaphthene and a series of selected molecular model compounds were combined with quantum-chemical calculations carried out on oligomers within the Austin model 1 (AMI) and valence-effective Hamiltonian (VEH) methodologies in order to study the differences among planar aromatic, non-planar aromatic, and quinoid polythiophene and polyisothianaphthene. 

MNDO/MM Modified neglect of differential overlap/molecuiar mechanical. MNDO is a semiempirical Hamiltonian. Hydrogen bonding poorly handled, therefore, not generally useful. (Refs. 39, 40) Austin model l/molecular mechanical. MNDO is a semiempirical Hamiltonian. Hydrogen bonding treated, but geometric details poorly reproduced. (Ref. 16) Depends on system 3 to 7 kcal mol ... 

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