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

Calculated Ionization Energy for He (Helium atom)

Experimental Ionization Energy is 24.58741 eV

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Ionization Energies in eV

Methods with predefined basis sets

semi-empirical	PM6
composite	G1	24.446
	G2MP2	24.543
	G2	24.543
	G3	24.570
	G3B3	24.583
	G3MP2	24.553
	G4	24.586
	CBS-Q	24.609

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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-pVDZ	daug-cc-pVTZ
hartree fock	HF	23.838	23.410	23.410	23.444	23.444	23.444	23.444	23.450	23.450	23.444	23.450	23.450	23.444	23.463	23.448	23.438	23.463	23.448	23.433	23.463
density functional	LSDA	24.659	24.577	24.577	24.713	24.713	24.713	24.713	24.766	24.766	24.713			24.713	24.782
	BLYP	24.891	24.563	24.563	24.710	24.710	24.710	24.710	24.791	24.791	24.710	24.791	24.791	24.710	24.809		24.779	24.817		24.777	24.817
	B1B95	24.905	24.539	24.539	24.645	24.645	24.645	24.645	24.693	24.693	24.645	24.693	24.693	24.645	24.706		24.677	24.710		24.674	24.710
	B3LYP	25.085	24.746	24.746	24.868	24.868	24.868	24.868	24.926	24.926	24.868	24.926	24.926	24.868	24.940	24.939	24.914	24.946	24.941	24.911	24.946
	B3LYPultrafine		24.746			24.868	24.868	24.868	24.926		24.868	24.926	24.926	24.868	24.940		24.914	24.946		24.911	24.946
	B3PW91	24.942	24.561	24.561	24.664	24.664	24.664	24.664	24.709	24.709	24.664	24.709	24.709	24.665	24.722		24.696	24.726		24.693	24.726
	mPW1PW91	24.834	24.421	24.421	24.530	24.530	24.530	24.530	24.578	24.578	24.530	24.578	24.578	24.530	24.593		24.562	24.598		24.559	24.598
	M06-2X	24.956	24.489	24.489	24.690	24.690	24.690	24.690	24.677	24.677	24.690	24.677	24.677	24.691	24.692		24.723	24.695		24.720	24.695
	PBEPBE	24.587	24.236	24.236	24.382	24.382	24.382	24.382	24.449	24.449	24.382	24.449	24.449	24.383	24.464		24.443	24.472		24.441	24.472
	PBEPBEultrafine		24.236			24.382	24.382	24.382	24.449		24.382	24.449	24.449	24.383	24.464		24.443	24.472		24.441	24.472
	PBE1PBE	24.667	24.280	24.280	24.395	24.395	24.395	24.395	24.439	24.439	24.395	24.439	24.439	24.395	24.451		24.430	24.456		24.427	24.456
	HSEh1PBE	24.684	24.290	24.290	24.413	24.413	24.413	24.413	24.457	24.457	24.413	24.457	24.457	24.414	24.467		24.448	24.471		24.445	24.471
	TPSSh		24.577	24.577	24.693	24.693	24.693	24.693	24.729	24.729	24.693	24.729	24.729	24.693	24.742	24.730	24.719	24.748	24.732	24.716	24.748
	wB97X-D		24.581	24.581	24.637	24.637	24.637	24.637	24.704	24.704	24.637	24.704	24.704	24.637	24.723	24.716	24.661	24.727	24.719	24.658	24.727
	B97D3		24.726	24.726	24.855	24.855	24.855	24.855	24.932	24.932	24.855	24.932	24.932	24.855	24.953	24.928	24.904	24.961	24.932	24.901	24.961
		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-pVDZ	daug-cc-pVTZ
Moller Plesset perturbation	MP2	23.838	23.723	23.723	23.749	23.749	24.137	24.137	23.801	24.121	24.137	24.249	24.176	24.146	24.364	24.414	24.172	24.378	24.420	24.169	24.379
	MP2=FULL	23.838	23.723	23.723	23.749	23.749	24.137	24.137	23.801	24.121	24.137	24.249	24.176	24.146	24.364	24.414	24.172	24.378	24.420	24.169	24.379
	MP3					23.827		24.285				24.395	24.317	24.293	24.499					24.320	24.510
	MP3=FULL		23.795	23.795	23.827	23.827	24.285	24.285	23.874	24.253	24.285	24.395	24.317	24.293	24.499		24.323	24.509		24.320	24.510
	MP4		23.811			23.846				24.278		24.421	24.343	24.321	24.521		24.353	24.531		24.350	24.532
	MP4=FULL		23.811			23.846				24.278		24.421		24.321	24.521		24.353	24.531		24.350	24.532
	B2PLYP		24.357	24.357	24.446	24.446	24.563	24.563	24.495	24.593	24.563	24.630	24.608	24.565	24.672		24.600	24.679		24.596	24.680
	B2PLYP=FULL		24.357	24.357	24.446	24.446	24.563	24.563	24.495	24.593	24.563	24.630	24.608	24.565	24.672		24.600	24.679		24.596	24.680
	B2PLYP=FULLultrafine		24.357	24.357	24.446	24.446	24.563	24.563	24.495	24.593	24.563	24.630	24.608	24.565	24.672		24.600	24.679		24.596	24.680
Configuration interaction	CID		23.815	23.815	23.852	23.852			23.896			24.425		24.326	24.525					24.356	24.536
	CISD		23.815	23.815	23.852	23.852			23.899			24.426		24.326	24.526					24.356	24.536
		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-pVDZ	daug-cc-pVTZ
Quadratic configuration interaction	QCISD		23.815	23.815	23.852	23.852	24.320	24.320	23.899	24.284	24.320	24.426	24.349	24.326	24.526		24.359	24.536		24.356	24.536
	QCISD(T)					23.852			23.899			24.426	24.349	24.326	24.526		24.359	24.536		24.356	24.536
	QCISD(T)=FULL					23.852		24.320				24.426		24.326	24.526	24.561	24.359	24.536	24.564	24.356	24.536
Coupled Cluster	CCD		23.815	23.815	23.852	23.852	24.320	24.320	23.896	24.282	24.320	24.425	24.348	24.326	24.525		24.358	24.535		24.356	24.536
	CCSD					23.852	24.320	24.320	23.899	24.284	24.320	24.426	24.349	24.326	24.526	24.561	24.359	24.536	24.564	24.356	24.536
	CCSD=FULL					23.852					24.320	24.426	24.349	24.326	24.526	24.561	24.359	24.536	24.564	24.356	24.536
	CCSD(T)					23.852	24.320	24.320	23.899	24.284	24.320	24.426	24.349	24.326	24.526	24.561	24.359	24.536	24.564	24.356	24.536
	CCSD(T)=FULL					23.852						24.426	24.349	24.326	24.526	24.561	24.359	24.536	24.564	24.356	24.536
		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-pVDZ	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			23.450	23.450		23.444			23.450
density functional	BLYP									24.791
	B1B95									24.693
	B3LYP			24.926	24.926		24.868			24.926
	B3LYPultrafine									24.926
	B3PW91									24.709
	mPW1PW91									24.578
	M06-2X									24.677
	PBEPBE									24.449
	PBEPBEultrafine									24.449
	PBE1PBE									24.439
	HSEh1PBE									24.457
	TPSSh									24.729
	wB97X-D			24.704	24.704		24.637			24.704
	B97D3									24.932
Moller Plesset perturbation	MP2			23.801	23.801		23.749			24.353
	MP2=FULL									24.353
	MP3									24.486
	MP3=FULL									24.486
	MP4=FULL									24.508
	B2PLYP									24.659
	B2PLYP=FULL									24.659
	B2PLYP=FULLultrafine									24.659
Configuration interaction	CID									24.512
	CISD									24.512
Quadratic configuration interaction	QCISD									24.512
	QCISD(T)									24.512
	QCISD(T)=FULL									24.512
Coupled Cluster	CCD									24.512
	CCSD									24.512
	CCSD=FULL									24.512
	CCSD(T)									24.512
	CCSD(T)=FULL									24.512

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.