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

---

NIST policy on privacy, security, and accessibility.

---

© 2013 copyright by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved.

The National Institute of Standards and Technology (NIST) is an agency of the U.S. Department of Commerce.

Please send questions, comments, corrections, additions and suggestions to cccbdb@nist.gov.

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

Calculated Ionization Energy for C₃O₂ (Carbon suboxide)

Experimental Ionization Energy is 10.605 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.

---

Ionization Energies in eV

Methods with predefined basis sets

semi-empirical	PM3
composite	G2	10.569
	G3	10.558
	G3B3	10.641
	G4	537326.107

---

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	aug-cc-pVDZ	aug-cc-pVTZ	daug-cc-pVTZ
hartree fock	HF	5.691	9.315	9.315	9.290	9.211	9.211	9.322					9.292
density functional	LSDA	9.079	11.366	11.366	11.425	11.276	11.276	11.476	11.474	11.474	11.231			11.287	11.448	11.446
	BLYP	8.123	10.325	10.325	10.422	10.264	10.264	10.526	10.464	10.464	10.218			10.283
	B1B95	8.314	10.637	10.637	10.660	10.493	10.493	10.651	10.600	10.600	10.421			10.488
	B3LYP	8.274	10.604	10.604	10.675	10.504	10.504	10.716	10.667	10.667	10.444		10.716	10.508
	B3LYPultrafine					10.504
	B3PW91	8.373	10.747	10.747	10.745	10.571	10.571	10.721	10.692	10.692	10.494			10.568
	mPW1PW91	8.308	10.722	10.722	10.712	10.534	10.534	10.689	10.646	10.646	10.453			10.529
	M06-2X			10.814		10.606						10.774
	PBEPBE	8.329	10.578	10.578	10.615	10.453	10.453	10.661	10.605	10.605	10.390			10.467
	PBE1PBE					10.509
	HSEh1PBE		10.680			10.500		10.659
	TPSSh					10.436		10.595			10.360
	wB97X-D			10.686		10.496		10.643						11.072
	B97D3		10.582			10.403		10.588		10.536			10.588					10.548
		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	aug-cc-pVDZ	aug-cc-pVTZ	daug-cc-pVTZ
Moller Plesset perturbation	MP2	8.337	10.794	10.794									10.854
	MP2=FULL	8.339	10.796	10.796				11.050
	MP3=FULL							10.425
	MP4		10.750
	B2PLYP					10.436
	B2PLYP=FULLultrafine					10.438								10.439	10.652		10.706
Configuration interaction	CID		9.951	9.951
	CISD		9.843	9.843
		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	aug-cc-pVDZ	aug-cc-pVTZ	daug-cc-pVTZ
Quadratic configuration interaction	QCISD		9.595	9.595				10.123
Coupled Cluster	CCD		10.060	10.060
		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	aug-cc-pVDZ	aug-cc-pVTZ	daug-cc-pVTZ

---

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	9.163	9.104	9.263	9.278	9.288	9.292
density functional	B3LYP	10.678	10.453	10.754	10.597	10.817	10.806
	PBEPBE									10.618
Moller Plesset perturbation	MP2		10.842		10.992

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.