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	hartrees
Energy at 0K	-154.747329
Energy at 298.15K	-154.750415
HF Energy	-154.747329
Nuclear repulsion energy	99.043915

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3241	3140	0.00
2	A_g	1621	1571	0.00
3	A_g	1113	1078	0.00
4	A_g	953	924	0.00
5	A_u	899	871	0.00
6	A_u	540	523	0.00
7	B_1g	904	876	0.00
8	B_1u	3231	3130	15.81
9	B_1u	1629	1578	8.41
10	B_1u	1061	1028	0.03
11	B_2g	607	588	0.00
12	B_2u	3211	3111	11.40
13	B_2u	1267	1227	39.22
14	B_2u	702	680	9.39
15	B_3g	3195	3096	0.00
16	B_3g	1195	1158	0.00
17	B_3g	854	827	0.00
18	B_3u	591	572	139.36

Atom	y (Å)	z (Å)
C1	0.664	0.787
C2	0.664	-0.787
C3	-0.664	0.787
C4	-0.664	-0.787
H5	1.428	1.548
H6	1.428	-1.548
H7	-1.428	1.548
H8	-1.428	-1.548

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5738	1.3289	2.0598	1.0783	2.4568	2.2267	3.1355
C2	1.5738		2.0598	1.3289	2.4568	1.0783	3.1355	2.2267
C3	1.3289	2.0598		1.5738	2.2267	3.1355	1.0783	2.4568
C4	2.0598	1.3289	1.5738		3.1355	2.2267	2.4568	1.0783
H5	1.0783	2.4568	2.2267	3.1355		3.0964	2.8560	4.2125
H6	2.4568	1.0783	3.1355	2.2267	3.0964		4.2125	2.8560
H7	2.2267	3.1355	1.0783	2.4568	2.8560	4.2125		3.0964
H8	3.1355	2.2267	2.4568	1.0783	4.2125	2.8560	3.0964

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.915
C1	C3	C4	90.000	C1	C3	H7	135.085
C2	C1	C3	90.000	C2	C1	H5	134.915
C2	C4	C3	90.000	C3	C1	H5	135.085
C4	C2	H6	135.085	C4	C3	H7	134.915

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: B3LYP/aug-cc-pVQZ

States and conformations

	Computational Chemistry Comparison and Benchmark DataBase Release 22 (May 2022) Standard Reference Database 101 National Institute of Standards and Technology
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Calc. vs exp. Bad Vib. HF vs MP2 Bad scale factors Low excited states Oddities NaCN Is not linear FAQ Help Units Choose Units Energy Bond length Rotational Constant Moment of Inertia Dipole and Quadrupole Polarizability Explanations Hartree cm-1 Debye Credits Just show me Show me a calculated geometry Summary Using older interface Limit Basis sets Method options List Recent molecules Choose a few Molecules Number of atoms By heavy atoms Diatomics InChI Deuterated Dimers Geometry Point group Point group count Bonds types Isodesmic reactions Bad point group Multiple conformers, states Vibrations Big anharmonicity Energy Enthalpy at 0 Kelvin Similar molecules Similar Isomers Cis/trans Tautomers Multiple conformers, states Ions, Dipoles, etc. List Ions Ionization changes point group Dipole Quadrupole Polarizability Proton Affinities Index of CCCBDB Feedback Error form Wants
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Number	Element	Mulliken
1	C	-0.563
2	C	-0.563
3	C	-0.563
4	C	-0.563
5	H	0.563
6	H	0.563
7	H	0.563
8	H	0.563

<r²>	57.955
(<r²>)^1/2	7.613

All results from a given calculation for C4H4 (cyclobutadiene)

using model chemistry: B3LYP/aug-cc-pVQZ

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)