Best Estimates From Experiment

Theoretical Energies

Calculated Geometries

Errors in Theoretical Energies

Zero-Point Scaling Factors

Non-Hydrogen Transfer Reaction Barrier Heights Database

 

Minnesota Database Collection



database manager: Yan Zhao
Last updated June, 2006

Below are the descriptions of the databases that can be accessed from the links to the left.

Best Estimates From Experiment

This section contains our best estimates of atomization energies, ionization potentials, electron affinities, and reaction barrier heights. The data is largely based on experimental data.

Theoretical Energies

This section contains the raw energies from theoretical calculations. For most data, the energies are relative to infinitely seperated electrons and nuclei.

Calculated Geometries

This section contains the geometry of many molecules calculated at the QCISD/MG3 level of theory.

Errors in Theoretical Energies

This section gives the errors of different theoretical methods using various data sets or benchmarks detailed below.

Database/3 is a collection1 of experimental atomization energies, electron affinities, ionization potentials, and barrier heights.

The AE6 benchmark is the error in calculating the atomization energy for 6 small molecules. The molecules are SiH4, SiO, S2, propyne (C3H4), glyoxal (C2H2O2), and cyclobutane (C4H8). Similarly, the BH6 benchmark is the error in calculating 6 reactive barrier heights. The experimental atomization energies and barrier heights compared to are displayed below:

 

Molecule

De

propyne (C3H4)

704.79

glyoxal (C2H2O2)

633.35

cyclobutane (C4H8)

 1149.01

SiH4

322.40

SiO

192.08

S2

101.67

         

Reaction

V

 

(forward)

(reverse)

OH + CH4 → CH3 + H2O

6.7

19.6

H + OH → O + H2

10.7

13.1

H + H2S → HS + H2

3.6

17.3



Some methods are not defined for elements beyond the first row. To allow easy comparisons between these and other methods, the AE3 and BH4 benchmarks are subsets of AE6 and BH6 that include only 1st row elements and hydrogen, that is, that exclude any element heavier than Ne. Thus AE3 includes the first three molecules in AE6, and BH4 contains only the four barriers for the first two reactions in BH6.

In all tables at this web site, the mean errors for the atomization energy part of Database/3 and for AE6 and AE3 are given on a per bond basis. The mean errors per bond are obtained by dividing the mean signed error, mean unsigned error, or root-mean-square error for the molecules in the data set by the average number of bonds in the molecules of that data set.

Database

Average Number
of Bonds

Database/3

4.71

AE6

4.83

AE3

7.67



Gaussian94/98/03 input file of QCISD/MG3 optimized geometries for 22 saddle points used in Database/3

Gaussian94/98/03 input files QCISD/MG3 optimized geometries for all systems in Database/3

Download a PERL script to run the AE6 and BH6 benchmark with Gaussian 98 ae6bh6.pl

Zero-Point Scaling Factors

This is a list of zero-point energy scaling factors for many theoretical methods.  

Non-Hydrogen Transfer Reaction Barrier Heights Database

This is a page for a new database for Non-Hydrogen Transfer Reaction Barrier Heights.

References

1.    "Robust and Affordable Multicoefficient Methods for Thermochemistry and Thermochemical Kinetics: The MCCM/3 Suite and SAC/3" B. J. Lynch and D. G. Truhlar Journal of Physical Chemistry A, 107,
3898-3906 (2003).

2.    "Small Representative Benchmarks for Thermochemical Calculations" B. J. Lynch and D. G. Truhlar Journal of Physical Chemistry A, 107, 8996–8999. Erratum: submitted.