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	hartrees
Energy at 0K	-154.262402
Energy at 298.15K	-154.265422
HF Energy	-153.657779
Nuclear repulsion energy	98.703232

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3315	3131	0.00
2	A_g	1581	1493	0.00
3	A_g	1132	1069	0.00
4	A_g	980	925	0.00
5	A_u	828	782	0.00
6	A_u	524	495	0.00
7	B_1g	819	774	0.00
8	B_1u	3304	3120	11.35
9	B_1u	1590	1502	1.56
10	B_1u	1068	1009	0.30
11	B_2g	580	548	0.00
12	B_2u	3282	3100	4.04
13	B_2u	1268	1197	31.47
14	B_2u	737	696	6.70
15	B_3g	3268	3087	0.00
16	B_3g	1170	1105	0.00
17	B_3g	852	805	0.00
18	B_3u	583	551	107.49

Atom	y (Å)	z (Å)
C1	0.671	0.785
C2	0.671	-0.785
C3	-0.671	0.785
C4	-0.671	-0.785
H5	1.441	1.542
H6	1.441	-1.542
H7	-1.441	1.542
H8	-1.441	-1.542

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5697	1.3427	2.0656	1.0796	2.4509	2.2437	3.1426
C2	1.5697		2.0656	1.3427	2.4509	1.0796	3.1426	2.2437
C3	1.3427	2.0656		1.5697	2.2437	3.1426	1.0796	2.4509
C4	2.0656	1.3427	1.5697		3.1426	2.2437	2.4509	1.0796
H5	1.0796	2.4509	2.2437	3.1426		3.0844	2.8814	4.2209
H6	2.4509	1.0796	3.1426	2.2437	3.0844		4.2209	2.8814
H7	2.2437	3.1426	1.0796	2.4509	2.8814	4.2209		3.0844
H8	3.1426	2.2437	2.4509	1.0796	4.2209	2.8814	3.0844

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.548
C1	C3	C4	90.000	C1	C3	H7	135.452
C2	C1	C3	90.000	C2	C1	H5	134.548
C2	C4	C3	90.000	C3	C1	H5	135.452
C4	C2	H6	135.452	C4	C3	H7	134.548

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: MP2/6-31G(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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All results from a given calculation for C4H4 (cyclobutadiene)

using model chemistry: MP2/6-31G(2df,p)

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)