National Institute of Standards and Technology

Computational Chemistry Comparison and Benchmark DataBase
Release 22	May 2022
NIST Standard Reference Database 101

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XVII	Ion data
XVIII	Bad calculations
XIX	Index of properties
XX	H-bond dimers
XXI	Oddities

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XVII.C.1. (III.D.6.)

Calculated Ionization Energy for NaK (Sodium Potassium)

Experimental Ionization Energy is 4.41636 ± 0.00017 eV
Please note! These calculated ionizataion energies have the vibrational zero-point energy (zpe) included, but the zpe has NOT been scaled. Click on an entry for more details, including the ionization energy with a scaled zpe.

Original data displayed. Press to display differences.

Differences displayed. Press to display original data.

Ionization Energies in eV

Methods with predefined basis sets
composite	G2	4.420
	G3	4.470
	G3B3	4.472
	G4	4.374
	CBS-Q	4.199

Ionization Energies in eV

Methods with standard basis sets
		STO-3G	3-21G	3-21G*	6-31G	6-31G*	6-31G**	6-31+G**	6-311G*	6-311G**	6-31G(2df,p)	6-311+G(3df,2p)	TZVP
hartree fock	HF	-0.069	3.445	3.419	3.469	3.463	3.463	3.463	3.466	3.466	3.445		3.472
density functional	LSDA	2.437	5.034	5.034	5.102	5.100		5.099	5.099	5.099	5.090		5.089
	BLYP	1.701	4.549	4.538	4.543	4.546	4.546	4.547	4.542	4.542	4.535		4.534
	B1B95	1.366									4.290		4.296
	B3LYP	1.675	4.590	4.577	4.596	4.595	4.595	4.595	4.586	4.586	4.579		4.584
	B3LYPultrafine					4.595
	B3PW91	1.482	4.341	4.324	4.376	4.370	4.370	4.369	4.360	4.360	4.351		4.359
	mPW1PW91	1.414	4.377	4.358	4.379	4.373	4.373	4.372	4.362	4.362	4.352		4.361
	M06-2X	1.458	4.641	4.610	4.704	4.698	4.698	4.698	4.690		4.685	4.672	4.697
	PBEPBE	1.680	4.543	4.531	4.555	4.551	4.551	4.551	4.545	4.545	4.531		4.539
	HSEh1PBE	1.485	4.428	4.413	4.446	4.439	4.439		4.431	4.431	4.418		4.430
	TPSSh					4.390		4.389			4.367
	wB97X-D			4.180		4.280		4.279		4.282			4.260
		STO-3G	3-21G	3-21G*	6-31G	6-31G*	6-31G**	6-31+G**	6-311G*	6-311G**	6-31G(2df,p)	6-311+G(3df,2p)	TZVP
Moller Plesset perturbation	MP2	0.306		3.847	3.836	3.964	3.964	3.965	4.041	4.041	4.063
	MP2=FULL	0.368	3.813	3.883	3.840	3.978	3.978	3.980	4.072	4.072	4.107		3.860
	MP3					4.095
	MP3=FULL					4.109		4.110
	MP4		4.001			4.151				4.214
Configuration interaction	CID		4.037	4.072	4.066	4.127			3.962
Configuration interaction	CISD		4.045	4.076	4.074	4.133			3.967
		STO-3G	3-21G	3-21G*	6-31G	6-31G*	6-31G**	6-31+G**	6-311G*	6-311G**	6-31G(2df,p)	6-311+G(3df,2p)	TZVP
Quadratic configuration interaction	QCISD		4.045	4.076	4.076	4.178	4.178	4.179	4.221	4.221	4.246		4.062
Quadratic configuration interaction	QCISD(T)					4.190							4.062
Coupled Cluster	CCD		4.037	4.072	4.067	4.170	4.170	4.171	4.208	4.208	4.237		4.053
	CCSD					4.177
	CCSD(T)					4.190							4.062
	CCSD(T)=FULL					4.203							4.098
		STO-3G	3-21G	3-21G*	6-31G	6-31G*	6-31G**	6-31+G**	6-311G*	6-311G**	6-31G(2df,p)	6-311+G(3df,2p)	TZVP

Ionization Energies in eV

Methods with effective core potentials (select basis sets)
		CEP-31G	CEP-31G*	CEP-121G	CEP-121G*	LANL2DZ	SDD	cc-pVTZ-PP	aug-cc-pVTZ-PP	Def2TZVPP
hartree fock	HF	3.386		3.432		3.406	3.487
density functional	B3LYP	4.186		4.208		4.432	4.611
Moller Plesset perturbation	MP2						3.862

For descriptions of the methods (AM1, HF, MP2, ...) and basis sets (3-21G, 3-21G*, 6-31G, ...) see the glossary in section I.C. Predefined means the basis set used is determined by the method.