Some Common Methods of Computational Chemistrya
Method |
Applicability |
Cost |
Reliabilityb |
Type | Size |
Software | Computer | Personnel |
Accuracyc | Precisiond |
Empirical (e.g. Benson Groups) |
common organic |
any |
$ |
¢ |
$ |
A- |
B+ |
Molecular Mechanics (e.g. MM3) |
common organic |
100000 atoms |
$ |
¢¢¢ |
$$ |
A- |
B |
semi-empirical MO theory (e.g. MNDO/d) |
organic, some inorganic |
500 atoms |
$ |
$ |
$$ |
C+ |
C- |
density functional theory (e.g. B3LYP) |
alle |
50 atomsf |
$$$ |
$$ |
$$$ |
B- |
C+ |
CBS-4 (MO theory) |
alle |
20 atomsf |
$$$ |
$$$ |
$$$ |
B |
B- |
BAC-MP4 (corr. MO theory) |
organic, some inorganic |
20 atomsf |
$$$ |
$$$ |
$$$$ |
B+ |
B |
PCI-80 (corr. MO theory) |
alle |
20 atomsf |
$$$ |
$$$ |
$$$$ |
B+ |
B- |
G2 (MO theory) |
alle |
6 heaviesf |
$$$ |
$$$$ |
$$$ |
A- |
B |
CCSD(T) with basis set extrapolation (MO theory) |
alle |
3 heaviesf |
$$$ |
$$$$$$ |
$$$$ |
A |
A- |