I.

New molecules in release15b: Uracil, CH3OH-, CH3OH+, cytosine, CH2ClBr, ... more

Introduction

The CCCBDB contains links to:
Experimental and computational thermochemical data for a selected set of 1420 gas-phase atoms and molecules.
Tools for comparing experimental and computational ideal-gas thermochemical properties.

Citation	NIST Computational Chemistry Comparison and Benchmark Database NIST Standard Reference Database Number 101 Release 15b, August 2011, Editor: Russell D. Johnson III http://cccbdb.nist.gov/

A.	Description and use
	1.	Detailed summary of the CCCBDB
		Briefly, it consists of molecules with the following constraints: Well-established heat of formation. This allows accurate thermochemical comparisons. However we have started adding calculations on ions, very few of which have thermochemical data. Mostly atoms with atomic number less than 18 (Argon). Since release 11 we've added a few atoms from the K through Kr row (Ca, Ti, Cu, Zn, As, Se, and Br). Mostly less than six heavy atoms and twenty or fewer total atoms. The small size facilitates the use of common molecular orbital programs. We are adding some substituted benzenes (for example C₆H₅CH₃ toluene, C₆H₅CHCH₂ styrene, C₆H₅NH₂ aniline) and heterocycles (such as C₅H₅NO pyridinone) There are currently 1420 species in the CCCBDB, so not every molecule that meets the above criteria is included.
	2.	Using the CCCBDB
	3.	Index of properties in the CCCBDB
	4.	List showing how many calculations are currently in the CCCBDB
B.	Species in the CCCBDB
	1.	All the species in the CCCBDB
	2.	Species and properties you would like in the CCCBDB
	3.	Links to all experimental and all calculated data for one species
	4.	List of recently added molecules.
	5.	A calculated geometry for a molecule.
	To check whether or not a particular molecule is in the CCCBDB look at the "All experimental data for a given species" page in section II.A (experimental data section)
C.	Viewing Options
	1.	Choose units
		a.	Energy: kJ/mol or kcal/mol
		b.	Bond length: Å, pm, or a₀(bohr)
		c.	Rotational Constant: cm^-1 or GHz
		d.	Dipole and quadrupole: Debye or e a₀
		e.	Polarizability: a₀³ (bohr cubed) or Å³ (angstrom cubed)
		f.	Moment of inertia: amu Å² or gm cm²
	2.	Omit some methods and basis sets
		a.	Omit some methods
		b.	Omit some basis sets
D.	Information about quantum chemistry and thermochemistry
	1.	A glossary of computational terms.
	2.	A brief description of the thermochemical quantities and methods.
E.	Credits

Please send comments to cccbdb@nist.gov