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	hartrees
Energy at 0K	-153.659874
Energy at 298.15K	-153.663246
HF Energy	-153.659874
Nuclear repulsion energy	99.768167

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3412	3089	0.00
2	A_g	1773	1605	0.00
3	A_g	1208	1094	0.00
4	A_g	1028	931	0.00
5	A_u	1001	906	0.00
6	A_u	605	548	0.00
7	B_1g	982	889	0.00
8	B_1u	3400	3078	22.56
9	B_1u	1794	1624	5.06
10	B_1u	1156	1047	0.01
11	B_2g	711	644	0.00
12	B_2u	3375	3056	11.51
13	B_2u	1392	1260	37.39
14	B_2u	803	727	13.57
15	B_3g	3359	3041	0.00
16	B_3g	1289	1167	0.00
17	B_3g	918	831	0.00
18	B_3u	683	619	130.11

Atom	y (Å)	z (Å)
C1	0.658	0.783
C2	0.658	-0.783
C3	-0.658	0.783
C4	-0.658	-0.783
H5	1.420	1.536
H6	1.420	-1.536
H7	-1.420	1.536
H8	-1.420	-1.536

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5665	1.3152	2.0454	1.0717	2.4414	2.2101	3.1140
C2	1.5665		2.0454	1.3152	2.4414	1.0717	3.1140	2.2101
C3	1.3152	2.0454		1.5665	2.2101	3.1140	1.0717	2.4414
C4	2.0454	1.3152	1.5665		3.1140	2.2101	2.4414	1.0717
H5	1.0717	2.4414	2.2101	3.1140		3.0720	2.8408	4.1842
H6	2.4414	1.0717	3.1140	2.2101	3.0720		4.1842	2.8408
H7	2.2101	3.1140	1.0717	2.4414	2.8408	4.1842		3.0720
H8	3.1140	2.2101	2.4414	1.0717	4.1842	2.8408	3.0720

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.619
C1	C3	C4	90.000	C1	C3	H7	135.381
C2	C1	C3	90.000	C2	C1	H5	134.619
C2	C4	C3	90.000	C3	C1	H5	135.381
C4	C2	H6	135.381	C4	C3	H7	134.619

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: HF/6-31G(2df,p)

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	-0.158
2	C	-0.158
3	C	-0.158
4	C	-0.158
5	H	0.158
6	H	0.158
7	H	0.158
8	H	0.158

<r²>	56.862
(<r²>)^1/2	7.541

All results from a given calculation for C4H4 (cyclobutadiene)

using model chemistry: HF/6-31G(2df,p)

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)