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	hartrees
Energy at 0K	-154.636615
Energy at 298.15K	-154.639637
HF Energy	-154.636615
Nuclear repulsion energy	99.099076

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3243	3243	0.00
2	A_g	1658	1658	0.00
3	A_g	1125	1125	0.00
4	A_g	966	966	0.00
5	A_u	880	880	0.00
6	A_u	533	533	0.00
7	B_1g	874	874	0.00
8	B_1u	3233	3233	14.82
9	B_1u	1664	1664	3.67
10	B_1u	1052	1052	0.51
11	B_2g	568	568	0.00
12	B_2u	3210	3210	6.09
13	B_2u	1265	1265	37.56
14	B_2u	736	736	9.71
15	B_3g	3194	3194	0.00
16	B_3g	1178	1178	0.00
17	B_3g	841	841	0.00
18	B_3u	554	554	154.10

Atom	y (Å)	z (Å)
C1	0.664	0.785
C2	0.664	-0.785
C3	-0.664	0.785
C4	-0.664	-0.785
H5	1.431	1.548
H6	1.431	-1.548
H7	-1.431	1.548
H8	-1.431	-1.548

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5705	1.3280	2.0568	1.0815	2.4561	2.2292	3.1356
C2	1.5705		2.0568	1.3280	2.4561	1.0815	3.1356	2.2292
C3	1.3280	2.0568		1.5705	2.2292	3.1356	1.0815	2.4561
C4	2.0568	1.3280	1.5705		3.1356	2.2292	2.4561	1.0815
H5	1.0815	2.4561	2.2292	3.1356		3.0963	2.8611	4.2158
H6	2.4561	1.0815	3.1356	2.2292	3.0963		4.2158	2.8611
H7	2.2292	3.1356	1.0815	2.4561	2.8611	4.2158		3.0963
H8	3.1356	2.2292	2.4561	1.0815	4.2158	2.8611	3.0963

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.863
C1	C3	C4	90.000	C1	C3	H7	135.137
C2	C1	C3	90.000	C2	C1	H5	134.863
C2	C4	C3	90.000	C3	C1	H5	135.137
C4	C2	H6	135.137	C4	C3	H7	134.863

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: M06-2X/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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Number	Element	Mulliken
1	C	-0.219
2	C	-0.219
3	C	-0.219
4	C	-0.219
5	H	0.219
6	H	0.219
7	H	0.219
8	H	0.219

<r²>	57.642
(<r²>)^1/2	7.592

All results from a given calculation for C4H4 (cyclobutadiene)

using model chemistry: M06-2X/6-311G*

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)