National Institute of Standards and Technology
Computational Chemistry Comparison and Benchmark DataBase
Release 18October 2016
NIST Standard Reference Database 101
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XIXIndex of properties
XXH-bond dimers
XXIOddities

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

Calculated Ionization Energy for K (Potassium atom)

Experimental Ionization Energy is 4.34066 ± 0.00001 eV
Original data displayed. Press to display differences.
Differences displayed. Press to display original data.

Ionization Energies in eV
Methods with predefined basis sets
semi-empirical PM6  
composite G1 4.269
G2MP2 4.279
G2 4.271
G3B3 4.307
G3MP2 4.324
G4 4.317

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) TZVP cc-pVDZ
hartree fock HF 1.862 3.983 3.984 4.010 4.010 4.010 4.010 4.003 4.003 4.010 4.009  
ROHF   3.982 3.983 4.008 4.008 4.008 4.008 4.001 4.001      
density functional LSDA 3.463 4.824 4.834 4.887 4.917 4.917 4.917 4.915 4.915 4.917    
SVWN                     4.907  
BLYP 2.871 4.382 4.383 4.406 4.432 4.432 4.433 4.426 4.426 4.433    
B1B95     4.218 4.260 4.288 4.266 4.266 4.255 4.255 4.271    
B3LYP 2.895 4.452 4.453 4.480 4.502 4.502 4.502 4.494 4.494 4.502 4.489  
B3LYPultrafine         4.502              
B3PW91 2.736 4.318 4.320 4.364 4.373 4.373 4.373 4.365 4.365 4.377    
mPW1PW91 2.675 4.322 4.324 4.353 4.360 4.360 4.360 4.351 4.351 4.365    
M06-2X     4.271                  
PBEPBE 2.808 4.407 4.408 4.432 4.446 4.446 4.446 4.439 4.439 4.450    
PBE1PBE         4.377              
TPSSh         4.240   4.240     4.246    
wB97X-D     4.038   4.130   4.129   4.122   4.117 4.129
B97D3   3.941     3.970   3.970   3.961      
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) TZVP cc-pVDZ
Moller Plesset perturbation MP2 1.862 3.983 3.984 4.015 4.124 4.124 4.126 4.234 4.234 4.157 4.009  
MP2=FULL 1.896 3.989 4.020 4.015 4.124 4.124 4.126 4.237 4.237 4.157    
MP3             4.140          
MP3=FULL         4.140   4.142          
MP4   3.983     4.146       4.243      
Configuration interaction CID   3.983 3.984 4.017 4.141     4.198        
CISD   3.983 3.984 4.017 4.144     4.204        
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) TZVP cc-pVDZ
Quadratic configuration interaction QCISD   3.983 3.984 4.017 4.147 4.147 4.149 4.237 4.237 4.161    
QCISD(T)         4.148              
Coupled Cluster CCD   3.983 3.984 4.017 4.143 4.143 4.146 4.224 4.224 4.158    
CCSD         4.146              
CCSD(T)         4.148              
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) TZVP cc-pVDZ

Ionization Energies in eV
Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF         3.985 3.996
density functional B3LYP         4.445 4.497
Moller Plesset perturbation MP2         3.990 4.030
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.