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	hartrees
Energy at 0K	-154.527193
Energy at 298.15K	-154.530161
HF Energy	-154.527193
Nuclear repulsion energy	98.464733

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3167	3131	0.00
2	A_g	1581	1563	0.00
3	A_g	1079	1067	0.00
4	A_g	933	923	0.00
5	A_u	851	842	0.00
6	A_u	512	506	0.00
7	B_1g	858	848	0.00
8	B_1u	3156	3121	20.37
9	B_1u	1584	1566	6.29
10	B_1u	1023	1012	0.12
11	B_2g	578	571	0.00
12	B_2u	3135	3100	14.37
13	B_2u	1214	1201	40.24
14	B_2u	684	677	8.07
15	B_3g	3119	3084	0.00
16	B_3g	1146	1133	0.00
17	B_3g	814	805	0.00
18	B_3u	565	559	130.97

Atom	y (Å)	z (Å)
C1	0.669	0.789
C2	0.669	-0.789
C3	-0.669	0.789
C4	-0.669	-0.789
H5	1.440	1.557
H6	1.440	-1.557
H7	-1.440	1.557
H8	-1.440	-1.557

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5784	1.3386	2.0696	1.0881	2.4696	2.2451	3.1552
C2	1.5784		2.0696	1.3386	2.4696	1.0881	3.1552	2.2451
C3	1.3386	2.0696		1.5784	2.2451	3.1552	1.0881	2.4696
C4	2.0696	1.3386	1.5784		3.1552	2.2451	2.4696	1.0881
H5	1.0881	2.4696	2.2451	3.1552		3.1137	2.8809	4.2420
H6	2.4696	1.0881	3.1552	2.2451	3.1137		4.2420	2.8809
H7	2.2451	3.1552	1.0881	2.4696	2.8809	4.2420		3.1137
H8	3.1552	2.2451	2.4696	1.0881	4.2420	2.8809	3.1137

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.872
C1	C3	C4	90.000	C1	C3	H7	135.128
C2	C1	C3	90.000	C2	C1	H5	134.872
C2	C4	C3	90.000	C3	C1	H5	135.128
C4	C2	H6	135.128	C4	C3	H7	134.872

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: PBEPBEultrafine/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	-0.461
2	C	-0.461
3	C	-0.461
4	C	-0.461
5	H	0.461
6	H	0.461
7	H	0.461
8	H	0.461

<r²>	58.447
(<r²>)^1/2	7.645

All results from a given calculation for C4H4 (cyclobutadiene)

using model chemistry: PBEPBEultrafine/aug-cc-pVTZ

States and conformations

All results from a given calculation for C₄H₄ (cyclobutadiene)