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 CCl₂ (dichloromethylene)

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

composite	G4	9.235
	CBS-Q	9.248

---

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	daug-cc-pVTZ
hartree fock	HF	8.086	9.380	8.415	9.044	8.345	8.345	8.402	8.412	8.412	8.232		8.432	8.433	8.266	8.241	8.473	8.288	8.284
density functional	LSDA	9.150	10.370	9.495	10.080	9.455	9.455	9.574	9.576	9.576	9.413			9.544	9.508		9.672
	BLYP	8.677	9.864	9.029	9.589	8.930	8.930	9.074	9.066	9.066	8.862			8.980	8.950
	B1B95	8.941		9.049	9.635	8.935	8.965	9.057	9.057	9.057	8.915			9.060	8.941
	B3LYP	8.949	10.074	9.186	9.785	9.119	9.119	9.236	9.234	9.234	9.052		9.236	9.190	9.126		9.306	9.160
	B3LYPultrafine					9.119												9.161
	B3PW91	8.989	10.089	9.188	9.754	9.083	9.083	9.162	9.157	9.157	9.012			9.179	9.063
	mPW1PW91	8.967	10.018	9.148	9.723	9.012	9.012	9.096	9.087	9.125	8.978			9.108	8.991
	M06-2X			9.298		9.262						9.217
	PBEPBE	8.752	9.939	9.075	9.628	8.957	8.957	9.073	9.063	9.063	8.895			9.029	8.966
	PBE1PBE					9.013
	HSEh1PBE		10.006			9.002		9.090							8.994
	TPSSh					9.030		9.108			8.951				9.009
	wB97X-D			9.236		9.151		9.228		9.222			9.230	9.228	9.124			9.145
	B97D3		10.035			8.985		9.091		9.086		8.962	9.090		8.984			9.017	9.015
		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	daug-cc-pVTZ
Moller Plesset perturbation	MP2	7.633	9.415	8.614	9.135	8.637	8.637	8.748	8.740	8.739	8.930		8.820	8.846	9.011		9.112
	MP2=FULL		9.418	8.613	9.136	8.619	8.619	8.731	8.728	8.728				8.835	8.966
	MP3					8.789
	MP3=FULL					8.769		8.867
	MP4		9.579			8.705
	B2PLYP					8.896									9.028
	B2PLYP=FULLultrafine					8.890								9.014	9.014			9.071
Configuration interaction	CID		9.549	8.644	9.262	8.684			8.766
	CISD		9.495	8.623	9.200	8.650			8.736
		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	daug-cc-pVTZ
Quadratic configuration interaction	QCISD		9.529	8.726	9.233	8.746	8.746	8.849	8.847	8.847				8.948
	QCISD(T)					8.731
Coupled Cluster	CCD		9.624	8.770	9.342	8.832	8.832	8.926	8.925					9.032
	CCSD					8.770
	CCSD(T)														9.118
		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	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	9.180	8.508	9.138	8.477	9.277	9.140			8.219
density functional	B3LYP	9.967	9.313	9.909	9.280	9.953	9.848			9.071
	PBEPBE									8.914
Moller Plesset perturbation	MP2	9.290	8.941	9.294	8.974	9.292	9.232			8.969

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.