National Institute of Standards and Technology

Computational Chemistry Comparison and Benchmark DataBase
Release 21	August 2020
NIST Standard Reference Database 101

I	Introduction
II	Experimental data
III	Calculated data
IV	Data comparisons
V	Cost comparisons
VI	Input and output files
VII	Tutorials and Units
VIII	Links to other sites
IX	Feedback
X	Older CCCBDB versions
XII	Geometries
XIII	Vibrations
XIV	Reaction data
XV	Entropy data
XVI	Bibliographic data
XVII	Ion data
XVIII	Bad calculations
XIX	Index of properties
XX	H-bond dimers
XXI	Oddities

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The National Institute of Standards and Technology (NIST) is an agency of the U.S. Department of Commerce.

Please send questions, comments, corrections, additions and suggestions to cccbdb@nist.gov.

I.

New molecules in release21: NaAl, CH3CSNH2, C6H12O, C4H10O+, C6H6+, CH4-, ... more

Introduction

The CCCBDB contains:
Experimental and computational thermochemical data for a selected set of 2069 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 21, August 2020, 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 molecules with atoms from the K through Kr row (Ca, Sc, Ti, V, Cu, Zn, As, Se, and Br). Mostly less than nine heavy atoms and twenty or fewer total atoms. The small size facilitates the use of common molecular orbital programs. There are currently 2069 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