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	hartrees
Energy at 0K	-154.527189
Energy at 298.15K	-154.530156
HF Energy	-154.527189
Nuclear repulsion energy	98.465381

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3167	3147	0.00
2	A_g	1581	1571	0.00
3	A_g	1079	1072	0.00
4	A_g	933	927	0.00
5	A_u	851	846	0.00
6	A_u	512	509	0.00
7	B_1g	857	852	0.00
8	B_1u	3157	3136	20.38
9	B_1u	1584	1573	6.28
10	B_1u	1023	1017	0.12
11	B_2g	577	573	0.00
12	B_2u	3136	3115	14.38
13	B_2u	1214	1206	40.29
14	B_2u	683	679	8.05
15	B_3g	3119	3099	0.00
16	B_3g	1146	1138	0.00
17	B_3g	814	809	0.00
18	B_3u	565	561	130.97

Atom	y (Å)	z (Å)
C1	0.669	0.789
C2	0.669	-0.789
C3	-0.669	0.789
C4	-0.669	-0.789
H5	1.440	1.557
H6	1.440	-1.557
H7	-1.440	1.557
H8	-1.440	-1.557

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5784	1.3386	2.0696	1.0881	2.4695	2.2451	3.1551
C2	1.5784		2.0696	1.3386	2.4695	1.0881	3.1551	2.2451
C3	1.3386	2.0696		1.5784	2.2451	3.1551	1.0881	2.4695
C4	2.0696	1.3386	1.5784		3.1551	2.2451	2.4695	1.0881
H5	1.0881	2.4695	2.2451	3.1551		3.1137	2.8809	4.2420
H6	2.4695	1.0881	3.1551	2.2451	3.1137		4.2420	2.8809
H7	2.2451	3.1551	1.0881	2.4695	2.8809	4.2420		3.1137
H8	3.1551	2.2451	2.4695	1.0881	4.2420	2.8809	3.1137

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.871
C1	C3	C4	90.000	C1	C3	H7	135.129
C2	C1	C3	90.000	C2	C1	H5	134.871
C2	C4	C3	90.000	C3	C1	H5	135.129
C4	C2	H6	135.129	C4	C3	H7	134.871

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: PBEPBE/aug-cc-pVTZ

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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Number	Element	Mulliken
1	C	-0.460
2	C	-0.460
3	C	-0.460
4	C	-0.460
5	H	0.460
6	H	0.460
7	H	0.460
8	H	0.460

<r²>	58.447
(<r²>)^1/2	7.645

All results from a given calculation for C4H4 (cyclobutadiene)

using model chemistry: PBEPBE/aug-cc-pVTZ

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)