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
2H-pyrrole	C4H5N	→	C4H6N+	pyrrole, protonated

Bonding changes
Bond type C-C changed by -1 Bond type C=C changed by +1 Bond type C-N changed by +1 Bond type H-C changed by -1 Bond type C=N lost 1 Bond type H-N gained 2

Proton Affinities (kJ/mol)

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Proton Affinities in kJ/mol

Methods with predefined basis sets

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Proton Affinities in kJ/mol

Methods with standard basis sets

		3-21G*	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-pVTZ	daug-cc-pVTZ
hartree fock	HF		856										866
density functional	BLYP		845
	B3LYP						866					850
	M06-2X	889
	TPSSh		848	848			866				856
	wB97X-D	901	856	856		862			859	858	863	860
	B97D3							861
		3-21G*	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-pVTZ	daug-cc-pVTZ
Moller Plesset perturbation	MP2		837		830
	MP3=FULL		855
		3-21G*	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-pVTZ	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									867
density functional	B3LYP									851
	PBEPBE									843
Moller Plesset perturbation	MP2									842

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.