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	hartrees
Energy at 0K	-154.509842
Energy at 298.15K	-154.512789
HF Energy	-154.509842
Nuclear repulsion energy	98.302126

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3173	3144	0.00
2	A_g	1588	1573	0.00
3	A_g	1080	1070	0.00
4	A_g	935	927	0.00
5	A_u	843	835	0.00
6	A_u	514	509	0.00
7	B_1g	838	830	0.00
8	B_1u	3162	3133	28.50
9	B_1u	1590	1576	2.76
10	B_1u	1022	1012	0.53
11	B_2g	568	563	0.00
12	B_2u	3140	3112	17.02
13	B_2u	1211	1200	39.77
14	B_2u	686	680	7.58
15	B_3g	3124	3096	0.00
16	B_3g	1139	1128	0.00
17	B_3g	814	806	0.00
18	B_3u	561	556	129.70

Atom	y (Å)	z (Å)
C1	0.670	0.791
C2	0.670	-0.791
C3	-0.670	0.791
C4	-0.670	-0.791
H5	1.444	1.558
H6	1.444	-1.558
H7	-1.444	1.558
H8	-1.444	-1.558

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5814	1.3406	2.0732	1.0897	2.4731	2.2491	3.1603
C2	1.5814		2.0732	1.3406	2.4731	1.0897	3.1603	2.2491
C3	1.3406	2.0732		1.5814	2.2491	3.1603	1.0897	2.4731
C4	2.0732	1.3406	1.5814		3.1603	2.2491	2.4731	1.0897
H5	1.0897	2.4731	2.2491	3.1603		3.1166	2.8876	4.2487
H6	2.4731	1.0897	3.1603	2.2491	3.1166		4.2487	2.8876
H7	2.2491	3.1603	1.0897	2.4731	2.8876	4.2487		3.1166
H8	3.1603	2.2491	2.4731	1.0897	4.2487	2.8876	3.1166

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.779
C1	C3	C4	90.000	C1	C3	H7	135.221
C2	C1	C3	90.000	C2	C1	H5	134.779
C2	C4	C3	90.000	C3	C1	H5	135.221
C4	C2	H6	135.221	C4	C3	H7	134.779

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: PBEPBE/6-311G**

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	-0.096
2	C	-0.096
3	C	-0.096
4	C	-0.096
5	H	0.096
6	H	0.096
7	H	0.096
8	H	0.096

<r²>	58.331
(<r²>)^1/2	7.637

All results from a given calculation for C4H4 (cyclobutadiene)

using model chemistry: PBEPBE/6-311G**

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)