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.

III.F.2.

Completed calculations for C₂H (Ethynyl radical)

Methods and basis sets for which an energy has been calculated. "e" indicates just an energy has been calculated. "o" indicates an optimized geometry. "v" indicates vibrational frequencies. "s" followed by a number indicates completed calculations for different states (for example s1ov). "c" followed by a number indicates completed calculations for different conformations (for example c2ov).
See the Calculated Energies page (section III.A.1) for more calculated properties.

---

Methods with predefined basis sets

semi-empirical	PM3	c1ov
composite	G1	c1e
	G2MP2	c1e
	G2	c1e
	G3	c1e
	G3B3	c1e
	G3MP2	c1e
	G4	c1e
	CBS-Q	c1e

---

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	c1ov	c1ov	c1ov	c1ov	c1ov c2o	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1o c2o	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov
	ROHF		c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov			c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov
density functional	LSDA	c1ov	c1ov	c1ov	c1ov	c1o	c1ov c2ov	c1ov c2ov	c1ov	c1ov	c1ov c2ov		c1ov	c1ov c2ov	c1ov		c1ov c2ov	c1ov		c1ov
	BLYP	c1ov	c1ov c2ov	c1ov c2ov	c1ov c2ov	c1o c2ov	c1ov c2ov	c1ov c2ov	c1ov c2ov	c1ov c2ov	c1ov c2ov		c1o	c1ov c2ov	c1ov c2ov		c1ov c2ov	c1o		c1ov
	B1B95	c1ov	c1ov	c1ov	c1ov	c1ov c2ov	c1ov	c1ov c2ov	c1ov	c1ov	c1ov c2ov		c1ov	c1ov	c1ov		c1ov c2ov	c1ov c2ov		c1ov
	B3LYP	c1ov	c1ov	c1ov	c1ov	c1ov c2ov	c1ov c2ov	c1ov c2ov	c1ov	c1ov	c1ov	c1ov	c1o c2o	c1o c2o	c1ov	c1ov	c1ov c2ov	c1ov c2ov	c1ov	c1ov
	B3LYPultrafine		c1ov			c1ov c2ov	c1o c2ov	c1o c2ov	c1o c2ov				c1ov	c1o c2ov	c1ov		c1o	c1ov
	B3PW91	c1ov	c1ov	c1ov	c1ov	c1ov c2ov	c1ov	c1ov	c1ov	c1ov	c1ov		c1ov	c1ov	c1ov		c1ov	c1ov		c1ov
	mPW1PW91	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov		c1ov	c1ov	c1ov		c1ov	c1ov		c1ov
	M06-2X	c1ov	c1ov	c1ov	c1ov	c1o c2o	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov c2ov	c1ov	c1ov	c1ov		c1ov	c1ov
	PBEPBE	c1ov	c1ov	c1ov	c1o	c1ov c2ov	c1ov c2ov	c1ov c2ov	c1ov c2ov	c1ov c2ov	c1ov c2ov	c1ov c2ov	c1o	c1ov c2ov	c1ov c2ov		c1o c2o	c1o c2o		c1ov
	PBEPBEultrafine		c1ov			c1ov c2ov	c1o	c1o	c1o				c1o	c1o	c1o		c1o	c1o
	PBE1PBE	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov		c1ov	c1ov	c1ov		c1ov	c1ov
	HSEh1PBE	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1o c2o	c1ov	c1ov	c1ov		c1ov	c1ov	c1ov		c1ov	c1ov
	TPSSh	c1o	c1ov	c1ov	c1ov	c1o	c1o	c1o	c1ov	c1o	c1o		c1ov	c1o	c1ov	c1o	c1o	c1ov	c1o
	wB97X-D	c1o	c1o	c1ov	c1o	c1ov	c1o	c1ov	c1o	c1ov	c1o		c1ov	c1ov	c1ov	c1o	c1o	c1ov	c1o
	B97D3	c1o	c1o	c1o	c1o	c1ov	c1o	c1ov	c1o	c1ov	c1o	c1ov	c1ov	c1o	c1ov	c1o	c1o	c1o	c1o		c1ov c2ov
		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	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov		c1o c2o	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov
	MP2=FULL	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov		c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov
	PMP2					c1o		c1o
	ROMP2	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov		c1ov	c1ov	c1ov		c1o
	MP3					c1ov		c1ov					c1ov	c1ov	c1ov
	MP3=FULL		c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov		c1ov	c1ov	c1ov		c1ov	c1ov
	MP4		c1ov			c1ov			c1ov	c1ov			c1ov	c1ov	c1ov		c1ov	c1ov
	MP4=FULL		c1ov			c1ov				c1ov				c1ov	c1ov		c1ov	c1ov
	B2PLYP	c1ov	c1ov	c1ov	c1ov	c1o c2o	c1ov	c1ov	c1ov	c1ov	c1ov		c1ov	c1ov	c1ov		c1o	c1ov
	B2PLYP=FULL	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov		c1ov	c1ov	c1ov		c1o	c1ov
	B2PLYP=FULLultrafine	c1ov	c1ov	c1ov	c1ov	c1ov c2ov	c1ov	c1ov	c1ov	c1ov	c1ov		c1ov	c1ov c2ov	c1ov c2ov		c1o	c1ov c2ov
Configuration interaction	CID		c1ov	c1ov	c1ov	c1ov			c1ov
	CISD		c1ov	c1ov	c1ov	c1ov	c1ov		c1ov
		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		c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov		c1ov	c1ov	c1ov		c1ov	c1ov		c1ov
	QCISD(T)					c1ov			c1ov				c1ov	c1ov	c1ov		c1ov	c1dnf
	QCISD(T)=FULL					c1ov		c1ov						c1ov	c1ov	c1ov	c1ov	c1ov	c1ov
	QCISD(TQ)					c1ov		c1ov						c1ov	c1ov	c1ov	c1o	c1ov	c1o
	QCISD(TQ)=FULL					c1ov		c1ov						c1ov	c1ov	c1ov	c1o	c1ov	c1o
Coupled Cluster	CCD		c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov		c1ov	c1ov	c1ov		c1ov	c1ov
	CCSD					c1ov			c1ov		c1ov		c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov
	CCSD=FULL					c1ov					c1ov		c1ov	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov
	CCSD(T)					c1ov	c1ov	c1o	c1ov	c1o	c1o		c1ov	c1ov	c1ov	c1ov	c1o	c1ov	c1ov	c1ov
	CCSD(T)=FULL					c1ov							c1ov	c1ov	c1ov	c1ov	c1o	c1ov	c1ov
		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

---

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	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov			c1ov
density functional	B1B95		c1ov
	B3LYP	c1ov	c1ov	c1ov c2ov	c1ov c2ov	c1ov	c1ov			c1ov
	PBEPBE									c1o
	wB97X-D	c1o	c1o	c1o	c1o	c1o	c1o
Moller Plesset perturbation	MP2	c1ov	c1ov	c1ov	c1ov	c1ov	c1ov			c1ov

---

Single point energy calculations (select basis sets)

		6-311+G(3df,2p)	cc-pVDZ	cc-pVTZ	aug-cc-pVDZ	aug-cc-pVTZ	cc-pV(T+d)Z
Moller Plesset perturbation	MP2FC// HF/6-31G*	c1e	c1e	c1e	c1e	c1e	c1e
	MP2FC// B3LYP/6-31G*	c1e	c1e	c1e	c1e	c1e	c1e
	MP2FC// MP2FC/6-31G*	c1e	c1e	c1e	c1e	c1e	c1e
	MP4// HF/6-31G*	c1e		c1e			c1e
	MP4// B3LYP/6-31G*		c1e c2e	c1e c2e			c1e
	MP4// MP2/6-31G*	c1e		c1e			c1e
Coupled Cluster	CCSD// HF/6-31G*	c1e	c1e	c1e	c1e	c1e	c1e
	CCSD(T)// HF/6-31G*	c1e	c1e	c1e	c1e	c1e	c1e
	CCSD// B3LYP/6-31G*	c1e
	CCSD(T)// B3LYP/6-31G*	c1e c2e	c1e	c1e	c1e		c1e
	CCSD(T)//B3LYP/6-31G(2df,p)			c1e			c1e
	CCSD// MP2FC/6-31G*	c1e	c1e	c1e	c1e	c1e	c1e
	CCSD(T)// MP2FC/6-31G*	c1e	c1e	c1e	c1e	c1e	c1e

Barriers to internal rotation or inversion

---

Methods with predefined basis sets

semi-empirical	AM1	s1c1t1
	PM3	s1c1t1

---

Methods with standard basis sets

		3-21G	6-31G*	6-31+G**	cc-pVTZ	aug-cc-pVTZ
hartree fock	HF	s1c1t1	s1c1t1	s1c1t1	s1c1t1
	ROHF	s1c1t1	s1c1t1	s1c1t1	s1c1t1
density functional	B3LYP	s1c1t1	s1c1t1	s1c1t1	s1c1t1
		3-21G	6-31G*	6-31+G**	cc-pVTZ	aug-cc-pVTZ
Moller Plesset perturbation	MP2		s1c1t1	s1c1t1	s1c1t1
Coupled Cluster	CCSD(T)					s1c1t1
		3-21G	6-31G*	6-31+G**	cc-pVTZ	aug-cc-pVTZ

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.