National Institute of Standards and Technology

Computational Chemistry Comparison and Benchmark DataBase
Release 22	May 2022
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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IV.D.4. (XII.A.2.)

Comparison of experiment and theory for rCuCu

Species with coordinate rCuCu

Species	Name
Cu2	Copper diatomic

The small prefix is the number of bonds with completed calculations.
Click on an entry for a histogram of the difference distribution.

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rms differences (calculated - experiment) in Å

Methods with predefined basis sets

semi-empirical	PM6	1 0.045
composite	G2	1 0.068

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rms differences (calculated - experiment) in Å

Methods with standard basis sets

		3-21G	3-21G*	6-31G	6-31G*	6-31G**	6-31+G**	6-311G*	6-311G**	6-31G(2df,p)	6-311+G(3df,2p)	TZVP	cc-pVDZ	cc-pVTZ	aug-cc-pVTZ	daug-cc-pVTZ
hartree fock	HF	1 0.241	1 0.241	1 0.064	1 0.068	1 0.068	1 0.208	1 0.154	1 0.154	1 0.082		1 0.216				1 0.227
density functional	BLYP	1 0.062	1 0.062	1 0.196	2 0.175	1 0.203	1 0.046			1 0.210
	B3LYP	1 0.083	1 0.083	1 0.191	1 0.196	1 0.196	1 0.052	1 0.000	1 0.001	1 0.203		1 0.054
	B3LYPultrafine														1 0.011
	B3PW91	1 0.103	1 0.103	1 0.195	1 0.199	1 0.199	1 0.036	1 0.008	1 0.008	1 0.205
	mPW1PW91	1 0.113	1 0.113	1 0.192			1 0.039
	M06-2X		1 0.324		1 0.143						1 0.174
	PBEPBE	1 0.075	1 0.075	1 0.205	1 0.211	1 0.211	1 0.023	1 0.007	1 0.007	1 0.216
	PBE1PBE				1 0.196
	HSEh1PBE	1 0.337			1 0.198		1 0.037							1 0.045
	TPSSh				1 0.145		1 0.006			1 0.158				1 0.010
	wB97X-D		1 0.158		1 0.132		1 0.021		1 0.010			1 0.022	1 0.021	1 0.024	1 0.024
	B97D3	1 0.143			1 0.130		1 0.022		1 0.007		1 0.023	1 0.047		1 0.023	1 0.051	1 0.048
		3-21G	3-21G*	6-31G	6-31G*	6-31G**	6-31+G**	6-311G*	6-311G**	6-31G(2df,p)	6-311+G(3df,2p)	TZVP	cc-pVDZ	cc-pVTZ	aug-cc-pVTZ	daug-cc-pVTZ
Moller Plesset perturbation	MP2			1 0.162	2 0.165	1 0.191	1 0.031	2 0.006	1 0.007	1 0.204		1 0.079
	MP2=FULL			1 0.166	1 0.203	1 0.203	1 0.008	1 0.001	1 0.001	1 0.236
	MP3						1 0.092
	MP3=FULL				1 0.093		1 0.035
	MP4	1 0.073			1 0.212
	B2PLYP				1 0.197									1 0.021
	B2PLYP=FULLultrafine				1 0.200								1 0.049	1 0.038	1 0.033
Configuration interaction	CID			1 0.123	1 0.146			1 0.057	1 0.057
	CISD	1 0.507	1 0.507		1 0.152			1 0.053	1 0.053
		3-21G	3-21G*	6-31G	6-31G*	6-31G**	6-31+G**	6-311G*	6-311G**	6-31G(2df,p)	6-311+G(3df,2p)	TZVP	cc-pVDZ	cc-pVTZ	aug-cc-pVTZ	daug-cc-pVTZ
Quadratic configuration interaction	QCISD							1 0.026	1 0.026
Coupled Cluster	CCD						1 0.071	1 0.057	1 0.057	1 0.170
	CCSD(T)							1 0.047	1 0.043
		3-21G	3-21G*	6-31G	6-31G*	6-31G**	6-31+G**	6-311G*	6-311G**	6-31G(2df,p)	6-311+G(3df,2p)	TZVP	cc-pVDZ	cc-pVTZ	aug-cc-pVTZ	daug-cc-pVTZ

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rms differences (calculated - experiment) in Å

Methods with effective core potentials (select basis sets)

		CEP-31G	CEP-31G*	CEP-121G	CEP-121G*	LANL2DZ	SDD	cc-pVTZ-PP	aug-cc-pVTZ-PP	Def2TZVPP
hartree fock	HF	1 0.193		1 0.193		1 0.200	1 0.151			1 0.085
density functional	B3LYP	1 0.046		1 0.046		1 0.040	1 0.025			1 0.033
	PBEPBE									1 0.022
Moller Plesset perturbation	MP2	1 0.067		1 0.067		1 0.110	1 0.016			1 0.018

For descriptions of the methods (AM1, HF, MP2, ...) and basis sets (3-21G, 3-21G*, 6-31G, ...) see the glossary in section I.C. Predefined means the basis set used is determined by the method.