CCCBDB calculation results Page

State	Conformation	minimum conformation	conformer description	state description
1	1	yes	D2H	¹A_g
1	2	no	D4H	¹A_1g

Conformer 1 (D2H)

Jump to S1C2

Energy calculated at wB97X-D/6-311G**

	hartrees
Energy at 0K	-154.659056
Energy at 298.15K	-154.662199
HF Energy	-154.659056
Nuclear repulsion energy	99.067159

The energy at 298.15K was derived from the energy at 0K and an integrated heat capacity that used the calculated vibrational frequencies.

Vibrational Frequencies calculated at wB97X-D/6-311G**

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3277	3134	0.00
2	A_g	1663	1591	0.00
3	A_g	1137	1087	0.00
4	A_g	977	934	0.00
5	A_u	913	873	0.00
6	A_u	544	520	0.00
7	B_1g	914	874	0.00
8	B_1u	3265	3123	20.33
9	B_1u	1671	1598	3.27
10	B_1u	1074	1028	0.55
11	B_2g	622	595	0.00
12	B_2u	3242	3101	11.39
13	B_2u	1283	1227	40.96
14	B_2u	740	707	9.97
15	B_3g	3227	3087	0.00
16	B_3g	1206	1153	0.00
17	B_3g	856	819	0.00
18	B_3u	608	582	146.76

Unscaled Zero Point Vibrational Energy (zpe) 13608.1 cm^-1
Scaled (by 0.9565) Zero Point Vibrational Energy (zpe) 13016.1 cm^-1
See section III.C.1 List or set vibrational scaling factors to change the scale factors used here.
See section III.C.2 Calculate a vibrational scaling factor for a given set of molecules to determine the least squares best scaling factor.

Rotational Constants (cm^-1) from geometry optimized at wB97X-D/6-311G**

A	B	C
0.57261	0.42915	0.24530

See section I.F.4 to change rotational constant units

Geometric Data calculated at wB97X-D/6-311G**

Point Group is D_2h

Cartesians (Å)

Atom	y (Å)	z (Å)
C1	0.665	0.786
C2	0.665	-0.786
C3	-0.665	0.786
C4	-0.665	-0.786
H5	1.433	1.547
H6	1.433	-1.547
H7	-1.433	1.547
H8	-1.433	-1.547

Atom - Atom Distances (Å)

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5715	1.3295	2.0584	1.0814	2.4561	2.2314	3.1372
C2	1.5715		2.0584	1.3295	2.4561	1.0814	3.1372	2.2314
C3	1.3295	2.0584		1.5715	2.2314	3.1372	1.0814	2.4561
C4	2.0584	1.3295	1.5715		3.1372	2.2314	2.4561	1.0814
H5	1.0814	2.4561	2.2314	3.1372		3.0943	2.8654	4.2173
H6	2.4561	1.0814	3.1372	2.2314	3.0943		4.2173	2.8654
H7	2.2314	3.1372	1.0814	2.4561	2.8654	4.2173		3.0943
H8	3.1372	2.2314	2.4561	1.0814	4.2173	2.8654	3.0943

picture of cyclobutadiene state 1 conformation 1

More geometry information
Calculated Bond Angles

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	90.000	C1	C2	H6	134.755
C1	C3	C4	90.000	C1	C3	H7	135.245
C2	C1	C3	90.000	C2	C1	H5	134.755
C2	C4	C3	90.000	C3	C1	H5	135.245
C4	C2	H6	135.245	C4	C3	H7	134.755

Electronic energy levels

Charges, Dipole, Quadrupole and Polarizability
Charges from optimized geometry at wB97X-D/6-311G** Charges (e)

Number	Element	Mulliken
1	C	-0.109
2	C	-0.109
3	C	-0.109
4	C	-0.109
5	H	0.109
6	H	0.109
7	H	0.109
8	H	0.109

Electric dipole moments
Electric dipole components in Debye
(What's a Debye? See section VII.A.3)

	x	y	z	Total
	0.000	0.000	0.000	0.000
CHELPG
AIM
ESP

Electric Quadrupole moment
Quadrupole components in D Å

Primitive
	x	y	z
x	-26.625	0.000	0.000
y	0.000	-20.635	0.000
z	0.000	0.000	-21.788

Traceless
	x	y	z
x	-5.413	0.000	0.000
y	0.000	3.572	0.000
z	0.000	0.000	1.842

Polar
3z²-r²	3.684
x²-y²	-5.990
xy	0.000
xz	0.000
yz	0.000

Polarizabilities
Components of the polarizability tensor.
Units are Å³ (Angstrom cubed)
Change units.

	x	y	z
x	3.022	0.000	0.000
y	0.000	7.295	0.000
z	0.000	0.000	5.782

<r²> (average value of r²) Å²

<r²>	57.554
(<r²>)^1/2	7.586

Conformer 2 (D4H)

Jump to S1C1

Energy calculated at wB97X-D/6-311G**

	hartrees
Energy at 0K	-154.599414
Energy at 298.15K
HF Energy	-154.599414
Nuclear repulsion energy	99.777137

The energy at 298.15K was derived from the energy at 0K and an integrated heat capacity that used the calculated vibrational frequencies.

Vibrational Frequencies calculated at wB97X-D/6-311G**

Mode Number	Symmetry	Frequency (cm^-1)	Scaled Frequency (cm^-1)	IR Intensities (km mol^-1)
1	A_g	3354	3208	0.00
2	A_g	3152	3015	0.00
3	A_g	1318	1261	0.00
4	A_g	959	918	0.00
5	B_1g	1120	1072	0.00
6	B_1u	3344	3199	14.69
7	B_1u	1485	1420	79.24
8	B_1u	982	939	156.12
9	B_2g	461i	441i	0.00
10	B_2u	3157	3020	66.73
11	B_2u	1316	1259	153.89
12	B_2u	962	920	1.90
13	B_3g	2605	2492	0.00
14	B_3g	1204	1152	0.00
15	B_3g	1028	984	0.00
16	B_3u	951	910	1.83
17	B_3u	528	505	97.04
18	B_3u	459i	439i	171.85

Unscaled Zero Point Vibrational Energy (zpe) 13273.3 cm^-1
Scaled (by 0.9565) Zero Point Vibrational Energy (zpe) 12695.9 cm^-1
See section III.C.1 List or set vibrational scaling factors to change the scale factors used here.
See section III.C.2 Calculate a vibrational scaling factor for a given set of molecules to determine the least squares best scaling factor.

Rotational Constants (cm^-1) from geometry optimized at wB97X-D/6-311G**

A	B	C
0.55208	0.46277	0.25175

See section I.F.4 to change rotational constant units

Geometric Data calculated at wB97X-D/6-311G**

Point Group is D_2h

Cartesians (Å)

Atom	y (Å)	z (Å)
C1	0.000	1.067
C2	0.954	0.000
C3	-0.954	0.000
C4	0.000	-1.067
H5	0.000	2.143
H6	2.038	0.000
H7	-2.038	0.000
H8	0.000	-2.143

Atom - Atom Distances (Å)

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.4316	1.4316	2.1349	1.0759	2.3009	2.3009	3.2108
C2	1.4316		1.9078	1.4316	2.3460	1.0844	2.9923	2.3460
C3	1.4316	1.9078		1.4316	2.3460	2.9923	1.0844	2.3460
C4	2.1349	1.4316	1.4316		3.2108	2.3009	2.3009	1.0759
H5	1.0759	2.3460	2.3460	3.2108		2.9578	2.9578	4.2867
H6	2.3009	1.0844	2.9923	2.3009	2.9578		4.0767	2.9578
H7	2.3009	2.9923	1.0844	2.3009	2.9578	4.0767		2.9578
H8	3.2108	2.3460	2.3460	1.0759	4.2867	2.9578	2.9578

picture of cyclobutadiene state 1 conformation 2

More geometry information
Calculated Bond Angles

atom1	atom2	atom3	angle	atom1	atom2	atom3	angle
C1	C2	C4	96.430	C1	C2	H6	131.785
C1	C3	C4	96.430	C1	C3	H7	131.785
C2	C1	C3	83.570	C2	C1	H5	138.215
C2	C4	C3	83.570	C3	C1	H5	138.215
C4	C2	H6	131.785	C4	C3	H7	131.785

Electronic energy levels

Charges, Dipole, Quadrupole and Polarizability
Charges from optimized geometry at wB97X-D/6-311G** Charges (e)

Number	Element	Mulliken
1	C	-0.331
2	C	0.108
3	C	0.108
4	C	-0.331
5	H	0.098
6	H	0.125
7	H	0.125
8	H	0.098

Electric dipole moments
Electric dipole components in Debye
(What's a Debye? See section VII.A.3)

	x	y	z	Total
	0.000	0.000	0.000	0.000
CHELPG
AIM
ESP

Electric Quadrupole moment
Quadrupole components in D Å

Primitive
	x	y	z
x	-27.053	0.000	0.000
y	0.000	-18.253	0.000
z	0.000	0.000	-24.878

Traceless
	x	y	z
x	-5.488	0.000	0.000
y	0.000	7.713	0.000
z	0.000	0.000	-2.225

Polar
3z²-r²	-4.450
x²-y²	-8.800
xy	0.000
xz	0.000
yz	0.000

Polarizabilities
Components of the polarizability tensor.
Units are Å³ (Angstrom cubed)
Change units.

	x	y	z
x	3.156	0.000	0.000
y	0.000	6.780	0.000
z	0.000	0.000	7.713

<r²> (average value of r²) Å²

<r²>	56.791
(<r²>)^1/2	7.536

All results from a given calculation for C₄H₄ (cyclobutadiene)

using model chemistry: wB97X-D/6-311G**

States and conformations

Conformer 1 (D2H)

Conformer 2 (D4H)

	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: wB97X-D/6-311G**

States and conformations

Conformer 1 (D2H)

Conformer 2 (D4H)

All results from a given calculation for C₄H₄ (cyclobutadiene)