return to home page Computational Chemistry Comparison and Benchmark DataBase Release () Standard Reference Database 101 National Institute of Standards and Technology
You are here: FAQ Help > Using

Using the CCCBDB

The CCCBDB is set up to allow you to get experimental data, calculated data and comparisons between experimental and calculated data. The general design is to allow you to specify what you want in the following order:
1) choose a property (such as calculated vibrational frequencies)
2) choose a molecule (or molecules)
3) choose a calculational method and a basis set (such as B3LYP/6-31G*).

Choosing a property

The buttons at the top list several broad categories, which are subdivided into properties. For example the calculated button has subsections: Each of these is further divided into specific properties, such as rotational constants (under geometry; rotation) or Mulliken charges (under electrostatics; charges). Some of the properties may be found under several categories.

Specifying a molecule

When asked for a formula the CCCBDB can recognize entries such as CH3OH or (CH2)3O. The formula parser does not distinguish between different arrangements of the atoms: CH3COCH3 and C3H6O will both bring up a list of the five isomers of C3H6O present in the CCCBDB. A comma delimited list of molecules can also entered: CH4,C2H6,C3H8,C4H10. A few terms describing organic groups (such as "amines" or "ring5") will also provide a list of molecules.
Ions are entered by adding one or more + or - to the end of the formula: H3O+, NO3-, CO3--, PO4---
The formula parser can also handle Chemical Abstract Service (CAS) numbers and a few common names. Thus CH4, H2CH2, methane, and 74828 are all equivalent.
As well as using lists to specify a group of molecules there is a page for choosing molecules by atom types, bond types, and chemical groups. This page is accessed by clicking on the "choose chemical groups" link instead of entering a formula.

Older Interface

The CCCBDB used to use frames. The new interface uses a pull-down menu but an interface that looks like the older interface is still available at:
The new pages all end with an x. For example the new start page is
The old interface is