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
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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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XVII.C.1. (III.D.6.)

Calculated Ionization Energy for Be₂ (Beryllium diatomic)

Please note! These calculated ionizataion energies have the vibrational zero-point energy (zpe) included, but the zpe has NOT been scaled. Click on an entry for more details, including the ionization energy with a scaled zpe.

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Ionization Energies in eV

Methods with predefined basis sets

semi-empirical	PM3
composite	G2	7.508
	G3	7.516
	G3B3	7.527
	G4	7.543
	CBS-Q	7.423

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Ionization Energies in eV

Methods with standard basis sets

		STO-3G	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	cc-pVQZ	aug-cc-pVDZ	aug-cc-pVTZ	aug-cc-pVQZ	daug-cc-pVTZ
hartree fock	HF	4.400	6.298	6.298	6.037	5.953	5.953	6.098	6.151	6.151	5.945		5.947	6.184	6.149	6.143	6.167	6.147	6.142	5.645
density functional	LSDA	6.133	7.557	7.557	7.403	7.414	7.414	7.493	7.507	7.507	7.435			7.549	7.513		7.537
	BLYP	5.627	6.988	6.988	6.826	6.059	6.819	6.916	6.911	6.911	6.842			6.963	6.914
	B1B95	5.628	7.020	7.020	6.844	6.857	6.857	6.935	6.940	6.940	6.856			6.985	6.946		6.976
	B3LYP	5.687	7.097	7.097	6.927	6.918	6.918	7.009	7.015	7.015	6.938		6.889	7.065	7.017	7.015	7.056	7.017	7.015
	B3LYPultrafine					6.918												7.017
	B3PW91	5.603	7.039	7.039	6.880	6.880	6.880	6.946	6.956	6.956	6.891			6.998	6.958
	mPW1PW91	5.541	6.998	6.998	6.832	6.831	6.831	6.904	6.916	6.916	6.841			6.954	6.919
	M06-2X			6.043		6.787						6.025
	PBEPBE	5.662	7.059	7.059	6.906	6.910	6.910	6.988	6.988	6.988	6.919			7.034	6.989
	PBE1PBE					6.834
	HSEh1PBE		6.416			6.836									6.383
	TPSSh					6.305		6.367			6.315				6.409
	wB97X-D			6.203		6.042		6.114		6.150			6.108	6.114	6.165			6.167
	B97D3		6.238			6.083		6.152		6.164		6.187	6.148		6.190			6.197		6.198
		STO-3G	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	cc-pVQZ	aug-cc-pVDZ	aug-cc-pVTZ	aug-cc-pVQZ	daug-cc-pVTZ
Moller Plesset perturbation	MP2	5.257	7.019	7.019	6.807	5.828	6.759	6.868	6.002	6.953	6.830		6.617	6.953	6.985	7.007	6.949	6.992	7.014
	MP2=FULL	5.264	7.028	7.028	6.816	6.755	6.755	6.864	6.957	6.957	6.815			6.953	6.912	7.000	6.948		7.004
	MP3					7.104
	MP3=FULL					5.928		7.160
	MP4		7.624			7.232				7.397					7.392
	B2PLYP					6.828									6.978
	B2PLYP=FULLultrafine					5.984								6.130	6.162			6.167
Configuration interaction	CID		7.606	7.606	7.432	7.228			7.337
	CISD		7.510	7.510	7.326	7.110			7.221
		STO-3G	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	cc-pVQZ	aug-cc-pVDZ	aug-cc-pVTZ	aug-cc-pVQZ	daug-cc-pVTZ
Quadratic configuration interaction	QCISD		7.701	7.701	7.532	7.310	7.310	7.388	7.410	7.410	7.220			7.423	7.369
	QCISD(T)					7.237								7.384	7.382		7.381	7.384
Coupled Cluster	CCD		7.796	7.796	7.637	7.429	7.429	7.497	7.526	7.526	7.372			7.537	7.488		7.520	7.487
	CCSD					7.317
	CCSD(T)					7.299								7.388	7.384	7.385	7.385	7.386	7.387
	CCSD(T)=FULL					7.232										7.373			7.373
		STO-3G	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	cc-pVQZ	aug-cc-pVDZ	aug-cc-pVTZ	aug-cc-pVQZ	daug-cc-pVTZ

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Ionization Energies in eV

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	6.322	6.215	6.252	6.146	6.290	6.276			5.609
density functional	B3LYP	7.036	6.997	6.978	6.941	7.079	7.048			6.268
	PBEPBE									6.420
Moller Plesset perturbation	MP2	7.094	7.033	7.046	6.988	7.013	7.006			5.984

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.