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	hartrees
Energy at 0K	-154.613761
Energy at 298.15K	-154.616819
HF Energy	-154.613761
Nuclear repulsion energy	98.980333

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3265	3109	0.00
2	A_g	1659	1580	0.00
3	A_g	1130	1076	0.00
4	A_g	973	926	0.00
5	A_u	887	844	0.00
6	A_u	528	502	0.00
7	B_1g	892	849	0.00
8	B_1u	3256	3100	13.16
9	B_1u	1670	1590	7.56
10	B_1u	1061	1010	0.84
11	B_2g	589	561	0.00
12	B_2u	3234	3079	3.89
13	B_2u	1270	1210	40.69
14	B_2u	745	709	8.03
15	B_3g	3218	3064	0.00
16	B_3g	1188	1131	0.00
17	B_3g	837	797	0.00
18	B_3u	576	549	167.10

Atom	y (Å)	z (Å)
C1	0.667	0.784
C2	0.667	-0.784
C3	-0.667	0.784
C4	-0.667	-0.784
H5	1.435	1.547
H6	1.435	-1.547
H7	-1.435	1.547
H8	-1.435	-1.547

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5683	1.3331	2.0583	1.0826	2.4544	2.2356	3.1384
C2	1.5683		2.0583	1.3331	2.4544	1.0826	3.1384	2.2356
C3	1.3331	2.0583		1.5683	2.2356	3.1384	1.0826	2.4544
C4	2.0583	1.3331	1.5683		3.1384	2.2356	2.4544	1.0826
H5	1.0826	2.4544	2.2356	3.1384		3.0938	2.8698	4.2198
H6	2.4544	1.0826	3.1384	2.2356	3.0938		4.2198	2.8698
H7	2.2356	3.1384	1.0826	2.4544	2.8698	4.2198		3.0938
H8	3.1384	2.2356	2.4544	1.0826	4.2198	2.8698	3.0938

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.791
C1	C3	C4	90.000	C1	C3	H7	135.209
C2	C1	C3	90.000	C2	C1	H5	134.791
C2	C4	C3	90.000	C3	C1	H5	135.209
C4	C2	H6	135.209	C4	C3	H7	134.791

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: M06-2X/6-31+G**

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	-0.162
2	C	-0.162
3	C	-0.162
4	C	-0.162
5	H	0.162
6	H	0.162
7	H	0.162
8	H	0.162

<r²>	57.936
(<r²>)^1/2	7.612

All results from a given calculation for C4H4 (cyclobutadiene)

using model chemistry: M06-2X/6-31+G**

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)