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	hartrees
Energy at 0K	-154.442051
Energy at 298.15K	-154.445208
HF Energy	-154.442051
Nuclear repulsion energy	98.402230

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3328	3181	0.00
2	A_g	1651	1579	0.00
3	A_g	1135	1085	0.00
4	A_g	978	934	0.00
5	A_u	921	880	0.00
6	A_u	549	524	0.00
7	B_1g	903	863	0.00
8	B_1u	3312	3166	22.34
9	B_1u	1654	1581	1.93
10	B_1u	1086	1038	1.46
11	B_2g	653	624	0.00
12	B_2u	3288	3143	7.72
13	B_2u	1285	1229	38.50
14	B_2u	709	677	7.44
15	B_3g	3271	3127	0.00
16	B_3g	1219	1166	0.00
17	B_3g	877	838	0.00
18	B_3u	638	610	178.75

Atom	y (Å)	z (Å)
C1	0.671	0.791
C2	0.671	-0.791
C3	-0.671	0.791
C4	-0.671	-0.791
H5	1.440	1.550
H6	1.440	-1.550
H7	-1.440	1.550
H8	-1.440	-1.550

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5824	1.3415	2.0745	1.0806	2.4643	2.2431	3.1523
C2	1.5824		2.0745	1.3415	2.4643	1.0806	3.1523	2.2431
C3	1.3415	2.0745		1.5824	2.2431	3.1523	1.0806	2.4643
C4	2.0745	1.3415	1.5824		3.1523	2.2431	2.4643	1.0806
H5	1.0806	2.4643	2.2431	3.1523		3.0998	2.8803	4.2314
H6	2.4643	1.0806	3.1523	2.2431	3.0998		4.2314	2.8803
H7	2.2431	3.1523	1.0806	2.4643	2.8803	4.2314		3.0998
H8	3.1523	2.2431	2.4643	1.0806	4.2314	2.8803	3.0998

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.599
C1	C3	C4	90.000	C1	C3	H7	135.401
C2	C1	C3	90.000	C2	C1	H5	134.599
C2	C4	C3	90.000	C3	C1	H5	135.401
C4	C2	H6	135.401	C4	C3	H7	134.599

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: PBE1PBE/6-31G

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	-0.182
2	C	-0.182
3	C	-0.182
4	C	-0.182
5	H	0.182
6	H	0.182
7	H	0.182
8	H	0.182

<r²>	57.972
(<r²>)^1/2	7.614

All results from a given calculation for C4H4 (cyclobutadiene)

using model chemistry: PBE1PBE/6-31G

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)