MNDO, or Modified Neglect of Diatomic Overlap is a
semi-empirical 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 Diatomic Differential Overlap integral approximation. Similarly, this method replaced the earlier
MINDO method. It is part of the
MOPAC program and was developed in the group of
Michael Dewar. It is also part of the
AMPAC,
GAMESS (US),
PC GAMESS,
GAMESS (UK),
Gaussian,
ORCA and
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 ...
programs.
Later, it was essentially replaced by two new methods,
PM3 and
AM1, which are similar but have different parameterisation methods.
The extension by W. Thiel's group, called MNDO/d, which adds d functions, is widely used for
organometallic
Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and so ...
compounds. It is included in
GAMESS (UK).
MNDOC, also from W. Thiel's group, explicitly adds correlation effects though second order
perturbation theory
In mathematics and applied mathematics, perturbation theory comprises methods for finding an approximate solution to a problem, by starting from the exact solution of a related, simpler problem. A critical feature of the technique is a middle ...
with the parameters fitted to experiment from the correlated calculation. In this way, the method should give better results for systems where correlation is particularly important and different from that in the ground state molecules from the MNDO training set. This includes excited states and transition states. However, Cramer argues that "the model has not been compared to other NDDO models to the extent required to assess whether the formalism fulfills its potential."
References
MNDO
*
MNDO/d
*
*
MNDOC
*
*
*
* {{cite journal, journal=Journal of the American Chemical Society, volume=103, pages=1425, year=1981, doi=10.1021/ja00396a023, title=MNDOC study of excited states, last1=Schweig, first1=Armin, last2=Thiel, first2=Walter, issue=6
Semiempirical quantum chemistry methods