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	hartrees
Energy at 0K	-154.481939
Energy at 298.15K	-154.484879
HF Energy	-154.481939
Nuclear repulsion energy	97.906073

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3179	3161	0.00
2	A_g	1595	1586	0.00
3	A_g	1075	1069	0.00
4	A_g	927	922	0.00
5	A_u	844	839	0.00
6	A_u	512	510	0.00
7	B_1g	829	824	0.00
8	B_1u	3167	3149	26.30
9	B_1u	1599	1590	2.49
10	B_1u	1009	1003	0.26
11	B_2g	576	573	0.00
12	B_2u	3145	3127	13.86
13	B_2u	1202	1196	37.30
14	B_2u	688	684	7.18
15	B_3g	3128	3110	0.00
16	B_3g	1126	1119	0.00
17	B_3g	808	803	0.00
18	B_3u	563	560	99.27

Atom	y (Å)	z (Å)
C1	0.674	0.792
C2	0.674	-0.792
C3	-0.674	0.792
C4	-0.674	-0.792
H5	1.453	1.566
H6	1.453	-1.566
H7	-1.453	1.566
H8	-1.453	-1.566

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5836	1.3473	2.0792	1.0982	2.4830	2.2629	3.1749
C2	1.5836		2.0792	1.3473	2.4830	1.0982	3.1749	2.2629
C3	1.3473	2.0792		1.5836	2.2629	3.1749	1.0982	2.4830
C4	2.0792	1.3473	1.5836		3.1749	2.2629	2.4830	1.0982
H5	1.0982	2.4830	2.2629	3.1749		3.1315	2.9056	4.2718
H6	2.4830	1.0982	3.1749	2.2629	3.1315		4.2718	2.9056
H7	2.2629	3.1749	1.0982	2.4830	2.9056	4.2718		3.1315
H8	3.1749	2.2629	2.4830	1.0982	4.2718	2.9056	3.1315

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.807
C1	C3	C4	90.000	C1	C3	H7	135.193
C2	C1	C3	90.000	C2	C1	H5	134.807
C2	C4	C3	90.000	C3	C1	H5	135.193
C4	C2	H6	135.193	C4	C3	H7	134.807

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: PBEPBEultrafine/cc-pVDZ

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	0.018
2	C	0.018
3	C	0.018
4	C	0.018
5	H	-0.018
6	H	-0.018
7	H	-0.018
8	H	-0.018

<r²>	58.619
(<r²>)^1/2	7.656

All results from a given calculation for C4H4 (cyclobutadiene)

using model chemistry: PBEPBEultrafine/cc-pVDZ

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)