Computational Chemistry Comparison and Benchmark Database

R.D. Johnson III, NIST Computational Chemistry Comparison and Benchmark Database, NIST Standard Reference Database Number 101, Release 12,2005. Available at http //srdata.nist.gov/ cccbdb... 

The choice of fundamental approximation, combined with the choice of parameter values, defines a particular SEMOT method, analogous to a force field in MM. Several established and novel SEMOT methods have been reviewed and compared elsewhere [54]. Among the three popular SEMOT methods mentioned earlier, MNDO/d is least widely available in commercial software packages. The other two methods, AMI and PM3, differ only in their parameterization. Since the PM3 method was parameterized more recently and more carefully, it is expected to be more reliable and will be the focus of discussion here. However, performance varies, so it should be compared with that of the experiment for related systems before putting faith in the predictions. Note that AMI and PM3 predictions are included in the Computational Chemistry Comparison and Benchmark Database (CCCBDB), which is a convenient, on-line resource for comparing theoretical predictions with experimental data [55]. 

Jonhson RD III (ed) (2006) Computational chemistry comparison and benchmark database. NIST Standard reference database vol 101. http //www.srdata.nist.gov/cccbdb... 

CCCBDB NIST Computational Chemistry Comparison and Benchmark Database... 

Other publications, however, report more accurate values of B3LYP gas phase Gibbs free energy calculations on aliphatic amines, diamines, and aminoamines. In 2007 Bryantsev et al. reported that B3LYP calculations with the basis set 6-31-h-G had a mean absolute error of 0.78 kcal/mol from experimental values of the gas phase basicity (AGg s) of the reverse reaction of equation 1 reported in the NIST database [58]. This accuracy is comparable to that of expensive, high level model chemistries, but because the experimental values have uncertainties of 2 kcal/mol, it is difficult to discern exactly how accurate the calculations are in comparison to values in the other publications [81]. The take-home message remains the same always benchmark DFT calculations for the systems you are interested in computing [52]. 

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