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	hartrees
Energy at 0K	-153.133675
Energy at 298.15K	-153.136558
HF Energy	-152.767510
Nuclear repulsion energy	96.898569

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3300	3128	0.00
2	A_g	1522	1443	0.00
3	A_g	1123	1065	0.00
4	A_g	907	860	0.00
5	A_u	741	702	0.00
6	A_u	500	474	0.00
7	B_1g	828	785	0.00
8	B_1u	3283	3112	16.40
9	B_1u	1510	1432	2.57
10	B_1u	1077	1021	0.34
11	B_2g	552	523	0.00
12	B_2u	3261	3092	8.08
13	B_2u	1285	1218	31.36
14	B_2u	603	572	3.83
15	B_3g	3249	3080	0.00
16	B_3g	1221	1157	0.00
17	B_3g	888	842	0.00
18	B_3u	594	563	169.70

Atom	y (Å)	z (Å)
C1	0.679	0.811
C2	0.679	-0.811
C3	-0.679	0.811
C4	-0.679	-0.811
H5	1.448	1.570
H6	1.448	-1.570
H7	-1.448	1.570
H8	-1.448	-1.570

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.6228	1.3589	2.1166	1.0802	2.5027	2.2589	3.1936
C2	1.6228		2.1166	1.3589	2.5027	1.0802	3.1936	2.2589
C3	1.3589	2.1166		1.6228	2.2589	3.1936	1.0802	2.5027
C4	2.1166	1.3589	1.6228		3.1936	2.2589	2.5027	1.0802
H5	1.0802	2.5027	2.2589	3.1936		3.1406	2.8963	4.2722
H6	2.5027	1.0802	3.1936	2.2589	3.1406		4.2722	2.8963
H7	2.2589	3.1936	1.0802	2.5027	2.8963	4.2722		3.1406
H8	3.1936	2.2589	2.5027	1.0802	4.2722	2.8963	3.1406

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.632
C1	C3	C4	90.000	C1	C3	H7	135.368
C2	C1	C3	90.000	C2	C1	H5	134.632
C2	C4	C3	90.000	C3	C1	H5	135.368
C4	C2	H6	135.368	C4	C3	H7	134.632

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: MP2=FULL/3-21G*

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=FULL/3-21G*

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)