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	hartrees
Energy at 0K	-154.736859
Energy at 298.15K	-154.739945
HF Energy	-154.736859
Nuclear repulsion energy	99.007072

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3241	3135	0.00
2	A_g	1622	1570	0.00
3	A_g	1110	1074	0.00
4	A_g	952	921	0.00
5	A_u	896	867	0.00
6	A_u	537	520	0.00
7	B_1g	902	872	0.00
8	B_1u	3231	3126	15.87
9	B_1u	1629	1576	8.48
10	B_1u	1060	1025	0.03
11	B_2g	608	589	0.00
12	B_2u	3210	3105	11.41
13	B_2u	1263	1222	39.31
14	B_2u	699	676	9.33
15	B_3g	3194	3090	0.00
16	B_3g	1193	1154	0.00
17	B_3g	852	824	0.00
18	B_3u	590	571	139.73

Atom	y (Å)	z (Å)
C1	0.665	0.787
C2	0.665	-0.787
C3	-0.665	0.787
C4	-0.665	-0.787
H5	1.429	1.549
H6	1.429	-1.549
H7	-1.429	1.549
H8	-1.429	-1.549

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5744	1.3293	2.0605	1.0788	2.4578	2.2276	3.1367
C2	1.5744		2.0605	1.3293	2.4578	1.0788	3.1367	2.2276
C3	1.3293	2.0605		1.5744	2.2276	3.1367	1.0788	2.4578
C4	2.0605	1.3293	1.5744		3.1367	2.2276	2.4578	1.0788
H5	1.0788	2.4578	2.2276	3.1367		3.0976	2.8575	4.2143
H6	2.4578	1.0788	3.1367	2.2276	3.0976		4.2143	2.8575
H7	2.2276	3.1367	1.0788	2.4578	2.8575	4.2143		3.0976
H8	3.1367	2.2276	2.4578	1.0788	4.2143	2.8575	3.0976

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.906
C1	C3	C4	90.000	C1	C3	H7	135.094
C2	C1	C3	90.000	C2	C1	H5	134.906
C2	C4	C3	90.000	C3	C1	H5	135.094
C4	C2	H6	135.094	C4	C3	H7	134.906

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: B3LYP/aug-cc-pVTZ

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	-0.457
2	C	-0.457
3	C	-0.457
4	C	-0.457
5	H	0.457
6	H	0.457
7	H	0.457
8	H	0.457

<r²>	57.997
(<r²>)^1/2	7.616

All results from a given calculation for C4H4 (cyclobutadiene)

using model chemistry: B3LYP/aug-cc-pVTZ

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)