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	hartrees
Energy at 0K	-154.646555
Energy at 298.15K	-154.649599
HF Energy	-154.646555
Nuclear repulsion energy	98.932656

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3249	3127	0.00
2	A_g	1642	1580	0.00
3	A_g	1120	1079	0.00
4	A_g	966	930	0.00
5	A_u	872	840	0.00
6	A_u	538	518	0.00
7	B_1g	864	831	0.00
8	B_1u	3237	3116	30.38
9	B_1u	1648	1587	3.06
10	B_1u	1056	1017	0.77
11	B_2g	585	563	0.00
12	B_2u	3215	3095	20.64
13	B_2u	1263	1216	40.36
14	B_2u	723	696	9.68
15	B_3g	3199	3079	0.00
16	B_3g	1182	1138	0.00
17	B_3g	846	814	0.00
18	B_3u	581	559	149.76

Atom	y (Å)	z (Å)
C1	0.666	0.786
C2	0.666	-0.786
C3	-0.666	0.786
C4	-0.666	-0.786
H5	1.434	1.550
H6	1.434	-1.550
H7	-1.434	1.550
H8	-1.434	-1.550

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5721	1.3311	2.0600	1.0833	2.4591	2.2339	3.1407
C2	1.5721		2.0600	1.3311	2.4591	1.0833	3.1407	2.2339
C3	1.3311	2.0600		1.5721	2.2339	3.1407	1.0833	2.4591
C4	2.0600	1.3311	1.5721		3.1407	2.2339	2.4591	1.0833
H5	1.0833	2.4591	2.2339	3.1407		3.1000	2.8673	4.2227
H6	2.4591	1.0833	3.1407	2.2339	3.1000		4.2227	2.8673
H7	2.2339	3.1407	1.0833	2.4591	2.8673	4.2227		3.1000
H8	3.1407	2.2339	2.4591	1.0833	4.2227	2.8673	3.1000

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.846
C1	C3	C4	90.000	C1	C3	H7	135.154
C2	C1	C3	90.000	C2	C1	H5	134.846
C2	C4	C3	90.000	C3	C1	H5	135.154
C4	C2	H6	135.154	C4	C3	H7	134.846

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: B3PW91/6-311G*

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	-0.200
2	C	-0.200
3	C	-0.200
4	C	-0.200
5	H	0.200
6	H	0.200
7	H	0.200
8	H	0.200

<r²>	57.661
(<r²>)^1/2	7.593

All results from a given calculation for C4H4 (cyclobutadiene)

using model chemistry: B3PW91/6-311G*

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)