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
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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 H₂CN (Dihydrogen cyanide radical)

Experimental Ionization Energy is 9.4 ± 0.1 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	10.350
	G3	10.430
	G3B3	10.342
	G4	10.338
	CBS-Q	10.444

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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	9.514	10.266	10.266	10.395	10.206	10.184	10.252	10.217	10.195	10.124		10.224	10.141	10.173	10.183	10.213	10.189	10.187	10.188
	ROHF		10.266	10.266	10.395	10.206	10.184	10.150	10.217	10.195				10.141	10.173		10.213	10.189
density functional	LSDA	9.576	10.585	10.585	10.739
	BLYP	9.153	10.036	10.036	10.199
	B1B95	9.360	10.189	10.189	10.306
	B3LYP	9.478	10.371	10.371	10.523	10.426									10.478
	B3PW91	9.581	10.477	10.477	10.586
	mPW1PW91	9.605	10.502	10.502	10.608
	M06-2X			10.366								10.428
	PBEPBE	9.297	10.208	10.208	10.335
	TPSSh					10.433
	wB97X-D			10.389														10.417
	B97D3		10.267										10.366					10.364		10.363
		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	8.104			9.723	9.911									10.200
	MP2=FULL	8.100			9.721
	ROMP2	8.579			10.122
	MP4		9.499
	B2PLYP=FULLultrafine					10.237								10.215	10.358			10.402
Configuration interaction	CID		9.755	9.755	9.919
	CISD		9.816	9.816	9.983
		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		9.844	9.844	10.022
Coupled Cluster	CCD		9.692	9.692	9.862													10.529
	CCSD(T)=FULL					45.110
		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	10.529	10.274	10.535	10.253	10.536	10.537			10.186
density functional	B3LYP	10.677		10.684		10.661	10.653
Moller Plesset perturbation	MP2	9.853

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.