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 H₂CO (Formaldehyde)

Experimental Ionization Energy is 10.885 ± 0.01 eV
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	10.913
	G3	10.877
	G3MP2	10.879
	G4	10.818
	CBS-Q	10.900

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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	cc-pV(T+d)Z	daug-cc-pVDZ	daug-cc-pVTZ
hartree fock	HF	6.937	9.242	9.242	9.358	9.340	9.324	9.423	9.358	9.345	9.284	9.409	9.400	9.281	9.359	9.386	9.392	9.394	9.394	9.359	9.385	9.391
density functional	LSDA		11.042	11.041			11.134	11.320		11.210	11.084			11.067	11.246		11.276
	BLYP	8.441	10.284	10.284	10.483	10.410	10.393	10.621	10.502	10.482	10.338	10.604	10.596	10.339	10.537		10.583	10.603		10.537	10.581	10.601
	B1B95	8.640	10.460	10.460	10.619	10.487	10.525	10.683	10.588	10.569	10.477	10.664	10.657	10.467	10.539		10.577	10.586		10.539		10.656
	B3LYP	8.649	10.540	10.540	10.722	10.649	10.632	10.821	10.719	10.700	10.577	10.803	10.797	10.574	10.744	10.782	10.781	10.799	10.799	10.744	10.778	10.797
	B3LYPultrafine		10.540			10.649	10.632	10.821	10.719		10.577	10.803	10.797	10.574	10.744		10.781	10.799			10.778	10.797
	B3PW91	8.695	10.593	10.593	10.729	10.655	10.637	10.784	10.703	10.683	10.579	10.758	10.754	10.576	10.707		10.741	10.752		10.707	10.736	10.750
	mPW1PW91	8.646	10.558	10.558	10.689	10.615	10.595	10.745	10.661	10.640	10.537	10.718	10.716	10.540	10.666		10.705	10.713		10.642	10.701	10.711
	M06-2X	8.757	10.728	10.728	10.831	10.759	10.737	10.877	10.827	10.805	10.704	10.887	10.880	10.671	10.863		10.831	10.905			10.828	10.902
	PBEPBE	8.549	10.419	10.419	10.579	10.501	10.481	10.673	10.568	10.545	10.426	10.650	10.646	10.429	10.591		10.637	10.651		10.591	10.634	10.649
	PBEPBEultrafine		10.419			10.502	10.481	10.673	10.568		10.426	10.650	10.646	10.429	10.591		10.638	10.651			10.634	10.649
	PBE1PBE	8.575	10.512	10.512	10.650	10.575	10.575	10.706	10.619	10.597	10.498	10.679	10.679	10.499	10.629		10.667	10.677			10.662	10.675
	HSEh1PBE	8.567	10.512	10.512	10.648	10.573	10.554	10.706	10.618	10.597	10.496	10.679	10.681	10.494	10.630		10.664	10.677			10.659	10.675
	TPSSh	8.551	10.462	10.462	10.586	10.513	10.495	10.650	10.562	10.542	10.437	10.623	10.627	10.431	10.577	10.611	10.605	10.626	10.627		10.600	10.624
	wB97X-D	8.665	10.589	10.589	10.726	10.661	10.648	10.792	10.699	10.682	10.583	10.753	10.740	10.777	10.686	10.720	10.739	10.729			10.733	10.726
	B97D3	8.651	10.488	10.488	10.617	10.546	10.529	10.702	10.604	10.584	10.472	10.676	10.678	10.477	10.619	10.658	10.663	10.675	10.676		10.659	10.673
		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	cc-pV(T+d)Z	daug-cc-pVDZ	daug-cc-pVTZ
Moller Plesset perturbation	MP2	7.933	10.430	10.430	10.711	10.790	10.848	11.028	10.817	10.890	10.956	11.213	10.986	10.779	11.147	11.275	11.100	11.260	11.320	11.147	11.099	11.260
	MP2=FULL	7.934	10.431	10.431	10.713	10.793	10.851	11.031	10.822	10.896	10.959	11.218	10.991	10.782	11.152	11.281	11.102	11.262	11.325		11.102	11.261
	MP3					10.489		10.770				10.872	10.653	10.499	10.814						10.774	10.907
	MP3=FULL		10.193	10.193	10.421	10.491	10.559	10.703	10.501	10.587	10.675	10.879	10.657	10.502	10.821		10.778	10.915			10.777	10.913
	MP4		10.296			10.566				10.710		11.031	10.802	10.583	10.962		10.906	11.077			10.906	11.077
	MP4=FULL		10.297			10.568				10.715		11.037		10.585	10.968		10.908	11.079			10.908	11.079
	B2PLYP	8.277	10.393	10.393	10.602	10.576	10.583	10.767	10.626	10.637	10.574	10.808	10.736	10.521	10.745		10.760	10.819			10.758	10.817
	B2PLYP=FULL	8.277	10.393	10.393	10.603	10.576	10.584	10.768	10.628	10.639	10.575	10.809	10.737	10.521	10.747		10.761	10.820			10.759	10.818
	B2PLYP=FULLultrafine					10.576												10.820			10.759	10.818
Configuration interaction	CID		10.110	10.110	10.324	10.339			10.354			10.656		10.333	10.601						10.572	10.681
	CISD			9.987	10.191	10.242			10.267			10.580		10.245	10.527						10.483	10.606
		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	cc-pV(T+d)Z	daug-cc-pVDZ	daug-cc-pVTZ
Quadratic configuration interaction	QCISD		10.006	10.006	10.227	10.297	10.375	10.529	10.324	10.415	10.475	10.692	10.493	10.318	10.635		10.590	10.726		10.635	10.588	10.725
	QCISD(T)					10.339			10.379			10.776	10.558	10.364			10.658	10.817			10.657	10.817
	QCISD(T)=FULL																				10.659	10.821
	QCISD(TQ)					10.330		10.567				10.752		10.354	10.693	10.806	10.640	10.792
	QCISD(TQ)=FULL																				10.640
Coupled Cluster	CCD		10.242	10.242	10.478	10.508	10.572	10.721	10.527	10.607	10.675	10.884	10.682	10.515	10.826		10.787	10.918			10.785
	CCSD					10.318	10.395	10.546	10.344	10.435	10.494	10.710	10.512	10.338	10.655	10.760	10.606	10.744			10.604	10.743
	CCSD=FULL					10.320					10.499	10.718	10.516	10.341	10.663	10.769	10.608	10.751			10.606	10.749
	CCSD(T)					10.346	10.425	10.586	10.386	10.480	10.543	10.784	10.564	10.370	10.723	10.838	10.664	10.825	10.876	10.723	10.663	10.825
	CCSD(T)=FULL					10.348						10.791	10.568	10.373	10.730	10.848	10.666	10.830	10.883		10.665
		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	cc-pV(T+d)Z	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	9.355	9.340	9.359	9.362	9.383	9.383			9.383
density functional	BLYP									10.574
	B1B95									10.640
	B3LYP	10.740	10.649	10.765	10.695	10.808	10.800			10.776
	B3LYPultrafine									10.776
	B3PW91									10.732
	mPW1PW91									10.694
	M06-2X									10.865
	PBEPBE									10.624
	PBEPBEultrafine									10.624
	PBE1PBE									10.657
	HSEh1PBE									10.659
	TPSSh									10.605
	wB97X-D	10.682	10.609	10.706	10.647	10.765	10.759			10.720
	B97D3									10.654
Moller Plesset perturbation	MP2	10.746	10.826	10.822	10.877	10.825	10.829			11.188
	MP2=FULL									11.192
	MP3									10.849
	MP3=FULL									10.854
	B2PLYP									10.780
	B2PLYP=FULL									10.782
Quadratic configuration interaction	QCISD									10.670
Coupled Cluster	CCD									10.861
	CCSD									10.689
	CCSD=FULL									10.694

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.