All results from a given calculation for C₄H₄ (cyclobutadiene)

Energy calculated at G4

	hartrees
Energy at 0K	-154.588296
Energy at 298.15K	-154.583530
HF Energy	-154.687384
Nuclear repulsion energy	98.776682

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 B3LYP/6-31G(2df,p)

Mode Number	Symmetry	Frequency (cm-1)	Scaled Frequency (cm-1)	IR Intensities (km mol-1)	Raman Act (Å4/u)	Dep P	Dep U
1	Ag	3255	3141	0.00
2	Ag	1636	1579	0.00
3	Ag	1113	1074	0.00
4	Ag	958	925	0.00
5	Au	865	835	0.00
6	Au	541	522	0.00
7	B1g	834	805	0.00
8	B1u	3243	3130	25.41
9	B1u	1643	1586	3.12
10	B1u	1068	1030	0.00
11	B2g	610	589	0.00
12	B2u	3220	3108	13.57
13	B2u	1261	1217	34.43
14	B2u	705	680	8.12
15	B3g	3204	3092	0.00
16	B3g	1162	1121	0.00
17	B3g	845	816	0.00
18	B3u	597	576	100.68

Unscaled Zero Point Vibrational Energy (zpe) 13381.0 cm^-1
Scaled (by 0.965) Zero Point Vibrational Energy (zpe) 12912.6 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 B3LYP/6-31G(2df,p)

A	B	C
0.56941	0.42604	0.24370

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

Geometric Data calculated at B3LYP/6-31G(2df,p)

Point Group is D_2h

Cartesians (Å)

Atom	x (Å)	y (Å)	z (Å)
C1	0.000	0.666	0.789
C2	0.000	0.666	-0.789
C3	0.000	-0.666	0.789
C4	0.000	-0.666	-0.789
H5	0.000	1.437	1.547
H6	0.000	1.437	-1.547
H7	0.000	-1.437	1.547
H8	0.000	-1.437	-1.547

Atom - Atom Distances (Å)

	C1	C2	C3	C4	H5	H6	H7	H8
C1		1.5789	1.3317	2.0656	1.0812	2.4608	2.2352	3.1436
C2	1.5789		2.0656	1.3317	2.4608	1.0812	3.1436	2.2352
C3	1.3317	2.0656		1.5789	2.2352	3.1436	1.0812	2.4608
C4	2.0656	1.3317	1.5789		3.1436	2.2352	2.4608	1.0812
H5	1.0812	2.4608	2.2352	3.1436		3.0948	2.8738	4.2233
H6	2.4608	1.0812	3.1436	2.2352	3.0948		4.2233	2.8738
H7	2.2352	3.1436	1.0812	2.4608	2.8738	4.2233		3.0948
H8	3.1436	2.2352	2.4608	1.0812	4.2233	2.8738	3.0948

More geometry information
Calculated Bond Angles

atom1	atom2	atom3	angle		atom1	atom2	atom3	angle
C1	C2	C4	90.000		C1	C2	H6	134.537
C1	C3	C4	90.000		C1	C3	H7	135.463
C2	C1	C3	90.000		C2	C1	H5	134.537
C2	C4	C3	90.000		C3	C1	H5	135.463
C4	C2	H6	135.463		C4	C3	H7	134.537

Electronic energy levels

Charges, Dipole, Quadrupole and Polarizability
Charges from optimized geometry at B3LYP/6-31G(2df,p) Charges (e)

Number	Element	Mulliken	CHELPG	AIM	ESP
1	C	-0.112
2	C	-0.112
3	C	-0.112
4	C	-0.112
5	H	0.112
6	H	0.112
7	H	0.112
8	H	0.112

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

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

	x	y	z
x	0.000	0.000	0.000
y	0.000	0.000	0.000
z	0.000	0.000	0.000

<r²> (average value of r²) Ų

<r2>	57.599
(<r2>)1/2	7.589

Energy calculated at G4

	hartrees
Energy at 0K	-154.520656
Energy at 298.15K	-154.516357
HF Energy	-154.628493
Nuclear repulsion energy	99.572234

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 B3LYP/6-31G(2df,p)

Rotational Constants (cm^-1) from geometry optimized at B3LYP/6-31G(2df,p)

A	B	C
0.56941	0.42604	0.24370

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

Geometric Data calculated at B3LYP/6-31G(2df,p)

Point Group is D_2h

Electronic energy levels

Charges, Dipole, Quadrupole and Polarizability