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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III.D.11.

Calculated Proton Affinity

Name	Species		Species	Name
Ethynyl radical	C2H	→	C2H2+	acetylene cation

Bonding changes
Bond type H-C changed by +1

Proton Affinities (kJ/mol)

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Proton Affinities in kJ/mol

Methods with predefined basis sets

composite	G2	734
	G3	732
	G3B3	721
	G3MP2	733
	G4	723
	CBS-Q	725

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Proton Affinities in kJ/mol

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-pVTZ
hartree fock	HF	855	736	736	756		792	783	776	784	800	788		782	789	789	782	789	789	789	790
	ROHF		789	789	753	828	834	811	814	777			777	822	824	782	775	782	782
density functional	LSDA		726	726			756	741		738	758			743	739		737
	BLYP	880	767	767	789	791	795	776	772	778	797			777	777		770			777
	B1B95	868	759	759	832	781	795	780	769	781	784		780	781	782		777	770		782
	B3LYP	885	771	771	795	798	803	784	781	788	810	787			790	788	781	786	788	790
	B3LYPultrafine		771			798	803	786	780				786	786	789			788
	B3PW91	876	762	762	789	795	801	789	780	786	803		786	788	788		784	788		788
	mPW1PW91	875	763	761	788	798	804	791	783	787	804		785	791	791		785	788		791
	M06-2X	864	750	750	773		784	771	761	766	785		767	769	767		765	767
	PBEPBE	869	753	753		781	786	770	764	770	788	768		771	770					770
	PBEPBEultrafine		753			781
	PBE1PBE	874	758	758	784	792	792	784	776	783	800		781	784	784		780	784
	HSEh1PBE	875		758	785	793	798		777	783	800		782	785			781	784
	TPSSh		768	768	795	502			786				791	521	793			792
	wB97X-D			770		804		797		794			794	796	798			797
	B97D3					834		820		826		824	799		803
		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-pVTZ
Moller Plesset perturbation	MP2	940	788	788	818	818	833	819	799	813	824			816	809	806	809	807	805	809
	MP2=FULL	940	788	788	818	817	832	818	799	813	822		813	816	810	805	810	808	804	810
	ROMP2	861	731	731	752	763	778	765	746	761	770		764	758	758
	MP3					831		847					829	831	824
	MP3=FULL		797	797	826	830	846	833	814	829	837		829	831	826		825	824
	MP4		787			821				818			819	820	812		811	810
	MP4=FULL		787			820				818				821	814		814	811
	B2PLYP	881	759	759	783		799	784	772		797		781	781	780			779
	B2PLYP=FULL	881	759	759	784	790	799	784	772	781	797		781	781	781			780
	B2PLYP=FULLultrafine	881	759	759	784		799	784	772	781	797		781
Configuration interaction	CID		787	787	814	823			808
	CISD		761	761	786	804			790
		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-pVTZ
Quadratic configuration interaction	QCISD		737	737	760	779	794	783	765	780	791		782	779	780		772	778		780
	QCISD(T)					773			759				776	772	770		764
	QCISD(T)=FULL					772		777						773	774	768	765	771	767
	QCISD(TQ)					771		774						769	769	766		766
	QCISD(TQ)=FULL					770		774						770	773			770
Coupled Cluster	CCD		789	789	818	826	841	829	810	824	835		825	827	821		821	820
	CCSD					781			767		792		784	781	781		775	780
	CCSD=FULL					780					792		784	781	785	780	775	783
	CCSD(T)					775	790		760				778	773	773	770		771	769	773
	CCSD(T)=FULL					774							778	774	777	771		774	770
		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-pVTZ

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Proton Affinities in kJ/mol

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	750	787	742	778	743	742			789
density functional	B3LYP	801	822	780	784	781	782			788
Moller Plesset perturbation	MP2	831	835	809	809	808	808			807

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.