MNDO
Encyclopedia
MNDO, or Modified 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 Neglect of Differential Diatomic 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
and CP2K
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 compounds. It is included in GAMESS (UK)
.
MNDOC, also from W. Thiel's group, explicitly adds correlation effects though second order perturbation theory
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 include excited states and transition states. However Cramer (see reference below) argues that "the model has not been compared to other NDDO models to the degree necessary to evaluate whether the formalism lives up to that potential.
Quantum mechanics
Quantum mechanics, also known as quantum physics or quantum theory, is a branch of physics providing a mathematical description of much of the dual particle-like and wave-like behavior and interactions of energy and matter. It departs from classical mechanics primarily at the atomic and subatomic...
calculation of molecular electronic structure in computational chemistry
Computational chemistry
Computational chemistry is a branch of chemistry that uses principles of computer science to assist in solving chemical problems. It uses the results of theoretical chemistry, incorporated into efficient computer programs, to calculate the structures and properties of molecules and solids...
. It is based on the Neglect of Differential Diatomic Overlap
NDDO
NDDO stands for neglect of diatomic differential overlap. The formalism was first introduced by John Pople and it is now the basis of most successful semiempirical methods. While INDO added all one-centre two electron integrals to the CNDO/2 formalism, NDDO adds all two centre integrals for...
integral approximation. Similarly, this method replaced the earlier MINDO
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 method of John Pople. It was developed by the group...
method. It is part of the MOPAC
MOPAC
In computational chemistry, MOPAC is a popular computer program designed to implement semi-empirical quantum chemistry algorithms, such as MINDO, MNDO, AM1, PM3, PM5, and . It was largely written in the group of Michael Dewar at University of Texas, Austin...
program and was developed in the group of Michael Dewar. It is also part of the AMPAC
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....
, GAMESS (US)
GAMESS (US)
GAMESS is a computational chemistry software program that stands for General Atomic and Molecular Electronic Structure System. The original code started on October 1, 1977 as a National Resources for Computations in Chemistry project. In 1981, the code base split into GAMESS and GAMESS variants,...
, PC GAMESS
PC GAMESS
PC GAMESS/Firefly is an ab initio computational chemistry program for Intel-compatible x86, x86-64 processors based on GAMESS sources. However, it has mostly been rewritten , especially in platform-specific parts , mathematic functions , and quantum chemical methods PC GAMESS/Firefly is an ab...
, GAMESS (UK)
GAMESS (UK)
GAMESS is a computational chemistry software program that stands for General Atomic and Molecular Electronic Structure System. The original code split in 1981 into GAMESS and GAMESS variants, which now differ significantly...
, GAUSSIAN
GAUSSIAN
Gaussian is a computational chemistry software program initially released in 1970 by John Pople and his research group at Carnegie-Mellon University as Gaussian 70. It has been continuously updated since then...
and CP2K
CP2K
CP2K is a freely available program, written in Fortran 95, to perform atomistic and molecular simulations of solid state, liquid, molecular and biological systems...
programs.
Later, it was essentially replaced by two new methods, PM3
PM3 (chemistry)
PM3, or Parameterized Model number 3, is a semi-empirical method for the quantum calculation of molecular electronic structure in computational chemistry. It is based on the Neglect of Differential Diatomic Overlap integral approximation....
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 compounds. It is included in GAMESS (UK)
GAMESS (UK)
GAMESS is a computational chemistry software program that stands for General Atomic and Molecular Electronic Structure System. The original code split in 1981 into GAMESS and GAMESS variants, which now differ significantly...
.
MNDOC, also from W. Thiel's group, explicitly adds correlation effects though second order perturbation theory
Perturbation theory
Perturbation theory comprises mathematical methods that are used to find an approximate solution to a problem which cannot be solved exactly, by starting from the exact solution of a related problem...
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 include excited states and transition states. However Cramer (see reference below) argues that "the model has not been compared to other NDDO models to the degree necessary to evaluate whether the formalism lives up to that potential.
MNDO
- Dewar, M. J. S. and Thiel, W., Journal of the American Chemical Society, 99, 4899, (1977).
MNDO/d
- Thiel, W. and Voityuk, A. A., Journal of Physical Chemistry, 100. 616, (1996).
- Thiel, W., Advances in Chemical Physics, 93, 703, (1996).
MNDOC
- Cramer, C. J., Essentials of Computational Chemistry, John Wiley, 2002, page 135.
- Thiel, W., Journal of the American Chemical Society, 103, 1413, 1421, (1981).
- Schweig, A, and Thiel, W., Journal of the American Chemical Society, 103, 1425, (1981),