Austin Model 1, or AM1, is a
semi-empirical method for the
quantum calculation of molecular electronic structure in
computational chemistry
Computational chemistry is a branch of chemistry that uses computer simulation to assist in solving chemical problems. It uses methods of theoretical chemistry, incorporated into computer programs, to calculate the structures and properties of mo ...
. 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.
AM1 was developed by
Michael Dewar and co-workers and published in 1985. AM1 is an attempt to improve the
MNDO 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
MNDO 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 scie ...
.
AM1 is implemented in the
MOPAC
MOPAC is a popular computer program used in computational chemistry. It is designed to implement semi-empirical quantum chemistry algorithms, and it runs on Windows, Mac, and Linux.
MOPAC2016 is the current version. MOPAC2016 is able to perform c ...
,
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 Chem ...
,
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 ...
,
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),
PC GAMESS,
GAMESS (UK), and
SPARTAN programs.
An extension of AM1 is
SemiChem Austin Model 1 (SAM1), which is implemented in the
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 Chem ...
program and which explicitly treats d-orbitals.
An extension of AM1 is
AM1* that is available in
VAMP software.
See also
*
Semi-empirical quantum chemistry method
Semi-empirical quantum chemistry methods are based on the Hartree–Fock formalism, but make many approximations and obtain some parameters from empirical data. They are very important in computational chemistry for treating large molecules where ...
s
Notes
References
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Semiempirical quantum chemistry methods
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