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 data (experiment and calculated) in the CCCBDB for C₄ (Carbon tetramer)

Property		Experiment	Calculated	Comparison
Energies Entropies	Enthalpy 298.15K	x
	Enthalpy 0K	x
	Energy 0K		1342
	Energy 298.15K		76
	Atomization Enthalpy 298.15K	x	35	x
	Atomization Enthalpy 0K	x	37	x
	Entropy (298.15K)	x	5	x
	Entropy at any temperature		5
	Integrated Heat Capacity	x	5	x
	Heat Capacity (Cp)	x	5	x
	Nuclear Repulsion Energy		1322
	HOMO-LUMO Energies		1149
	Barriers to Internal Rotation		0
Geometries	Cartesians		1303
	Internal Coordinates	x	1303	x
	Products of moments of inertia		1301
	Rotational Constants		1317
	Point Group		1324
Vibrations	Vibrational Frequencies	fun.	1308	x
	Vibrational Intensities		1731
	Zero-point energies		1308
	Vibrational scaling factors
	Anharmonic frequencies and constants
	Raman frequencies and intensities		838
Electronic States	Electronic states	x	620
Electrostatics	Atom charges		744
	Dipole		1023
	Quadrupole		837
	Polarizability		749
Other results	Spin		680
	Number of basis functions		101
	Conformations		1