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	hartrees
Energy at 0K	-154.550926
Energy at 298.15K	-154.554036
HF Energy	-154.550926
Nuclear repulsion energy	99.263201

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3262	3135	0.00
2	A_g	1649	1585	0.00
3	A_g	1124	1081	0.00
4	A_g	970	932	0.00
5	A_u	898	863	0.00
6	A_u	540	519	0.00
7	B_1g	898	863	0.00
8	B_1u	3252	3125	17.78
9	B_1u	1656	1591	3.54
10	B_1u	1060	1019	0.39
11	B_2g	611	587	0.00
12	B_2u	3230	3105	10.40
13	B_2u	1268	1219	40.90
14	B_2u	732	703	10.19
15	B_3g	3213	3088	0.00
16	B_3g	1192	1146	0.00
17	B_3g	845	812	0.00
18	B_3u	595	572	130.56

Atom	y (Å)	z (Å)
C1	0.664	0.783
C2	0.664	-0.783
C3	-0.664	0.783
C4	-0.664	-0.783
H5	1.429	1.545
H6	1.429	-1.545
H7	-1.429	1.545
H8	-1.429	-1.545

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5660	1.3271	2.0527	1.0802	2.4509	2.2269	3.1304
C2	1.5660		2.0527	1.3271	2.4509	1.0802	3.1304	2.2269
C3	1.3271	2.0527		1.5660	2.2269	3.1304	1.0802	2.4509
C4	2.0527	1.3271	1.5660		3.1304	2.2269	2.4509	1.0802
H5	1.0802	2.4509	2.2269	3.1304		3.0907	2.8576	4.2093
H6	2.4509	1.0802	3.1304	2.2269	3.0907		4.2093	2.8576
H7	2.2269	3.1304	1.0802	2.4509	2.8576	4.2093		3.0907
H8	3.1304	2.2269	2.4509	1.0802	4.2093	2.8576	3.0907

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.892
C1	C3	C4	90.000	C1	C3	H7	135.108
C2	C1	C3	90.000	C2	C1	H5	134.892
C2	C4	C3	90.000	C3	C1	H5	135.108
C4	C2	H6	135.108	C4	C3	H7	134.892

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: HSEh1PBE/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	-0.120
2	C	-0.120
3	C	-0.120
4	C	-0.120
5	H	0.120
6	H	0.120
7	H	0.120
8	H	0.120

<r²>	57.458
(<r²>)^1/2	7.580

All results from a given calculation for C4H4 (cyclobutadiene)

using model chemistry: HSEh1PBE/cc-pVTZ

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)