Austin Model 1, or AM1, is a

semi-empirical Empirical evidence is evidence obtained through sense experience or experimental procedure. It is of central importance to the sciences and plays a role in various other fields, like epistemology and law. There is no general agreement on how the ...

method for the

quantum In physics, a quantum (: quanta) is the minimum amount of any physical entity (physical property) involved in an interaction. The fundamental notion that a property can be "quantized" is referred to as "the hypothesis of quantization". This me ...

calculation of molecular electronic structure in

computational chemistry Computational chemistry is a branch of chemistry that uses computer simulations to assist in solving chemical problems. It uses methods of theoretical chemistry incorporated into computer programs to calculate the structures and properties of mol ...

. It is based on the Neglect of Differential Diatomic Overlap integral approximation. Specifically, it is a generalization of the modified neglect of differential diatomic overlap approximation. Related methods are PM3 and the older

MINDO MINDO, or Modified Intermediate Neglect of Differential Overlap is a semi-empirical method for the quantum calculation of molecular electronic structure in computational chemistry. It is based on the Intermediate Neglect of Differential Overlap ...

. AM1 was developed by Michael Dewar and co-workers and published in 1985. AM1 is an attempt to improve the

MNDO MNDO, or Modified Neglect of Diatomic Overlap is a semi-empirical method for the quantum calculation of molecular electronic structure in computational chemistry. It is based on the Neglect of Diatomic Differential Overlap integral approximation. ...

model by reducing the repulsion of atoms at close separation distances. The atomic core-atomic core terms in the MNDO equations were modified through the addition of off-center attractive and repulsive

Gaussian Carl Friedrich Gauss (1777–1855) is the eponym of all of the topics listed below. There are over 100 topics all named after this German mathematician and scientist, all in the fields of mathematics, physics, and astronomy. The English eponymo ...

functions. The complexity of the parameterization problem increased in AM1 as the number of parameters per atom increased from 7 in

to 13-16 per atom in AM1. The results of AM1 calculations are sometimes used as the starting points for parameterizations of forcefields in

molecular modelling Molecular modelling encompasses all methods, theoretical and computational, used to model or mimic the behaviour of molecules. The methods are used in the fields of computational chemistry, drug design, computational biology and materials scien ...

. AM1 is implemented in the

MOPAC MOPAC is a computational chemistry software package that implements a variety of semi-empirical quantum chemistry methods based on the neglect of diatomic differential overlap (NDDO) approximation and fit primarily for gas-phase thermochemistry ...

AMPAC AMPAC is a general-purpose semiempirical quantum chemistry program. It is marketed by Semichem, Inc. and was developed originally by Michael Dewar and his group. The first version of AMPAC (2.1) was made available in 1985 through the Quantum Che ...

CP2K CP2K is a freely available ( GPL) quantum chemistry and solid state physics program package, written in Fortran 2008, to perform atomistic simulations of solid state, liquid, molecular, periodic, material, crystal, and biological systems. It prov ...

GAMESS (US) General Atomic and Molecular Electronic Structure System (GAMESS (US)) is computer software for computational chemistry. The original code started on October 1, 1977 as a National Resources for Computations in Chemistry project. In 1981, the code ...

PC GAMESS Firefly, formerly named PC GAMESS, is an ab initio computational chemistry program for Intel-compatible x86, x86-64 processors based on GAMESS (US) sources. However, it has been mostly rewritten (60-70% of the code), especially in platform-spec ...

GAMESS (UK) General Atomic and Molecular Electronic Structure System (GAMESS-UK) is a computer software program for computational chemistry. The original code split in 1981 into GAMESS-UK and GAMESS (US) variants, which now differ significantly. Many of the e ...

, and SPARTAN programs. An extension of AM1 is SemiChem Austin Model 1 (SAM1), which is implemented in the

program and which explicitly treats d-orbitals. An extension of AM1 is

AM1* AM1* is a semiempirical molecular orbital technique in computational chemistry Computational chemistry is a branch of chemistry that uses computer simulations to assist in solving chemical problems. It uses methods of theoretical chemistry incor ...

that is available in

VAMP Vamp most commonly refers to: * Vamp (shoe), the upper part of a shoe * Vamp (woman), a seductress or ''femme fatale''; derived from "vampire" * Vamp (music), a repeating musical figure or accompaniment Vamp or vamps may also refer to: Science ...

software.

Notes

References

* * * * * Semiempirical quantum chemistry methods {{Quantum-chemistry-stub

See also

Notes

References