National Institute of Standards and Technology
Computational Chemistry Comparison and Benchmark DataBase
Release 18October 2016
NIST Standard Reference Database 101
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IIExperimental data
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XIII Vibrations
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XVEntropy data
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XVIIIon data
XVIIIBad calculations
XIXIndex of properties
XXH-bond dimers
XXIOddities

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

Calculated Ionization Energy for CH2 (Methylene)

Experimental Ionization Energy is 10.396 ± 0.003 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
semi-empirical AM1  
PM3  
PM6  
composite G2 10.296
G3 10.378
G3B3 10.478
G3MP2 10.380
G4 10.455
CBS-Q 10.320

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 cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z
hartree fock HF 8.365 9.778 9.778 9.697 9.626 9.615 9.691 9.684 9.682 9.603 9.702 9.648 9.681 9.688 9.679 9.687 9.689 9.674
ROHF   9.578 9.578 9.503 9.459 9.454 9.547 9.527 9.533   9.553 9.498 9.543 9.552 9.539 9.551 9.553 9.606
density functional LSDA 9.412 10.974 10.974 10.935 10.933 10.936 11.100 11.088 11.095 10.940 11.134 11.016 11.122   11.119 11.143   11.058
SVWN   10.974     10.933 10.936 11.100 11.088 11.095 10.940 11.066 11.016 11.122   11.119 11.143    
BLYP 8.728 10.131 10.131 10.108 10.089 10.089 10.280 10.244 10.249 10.092 10.305 10.183 10.284   10.305 10.316   10.234
B1B95 8.920 10.273 10.273 10.224 10.208 10.208 10.342 10.310 10.317 10.212 10.357 10.273 10.340   10.349 10.360   10.297
B3LYP 8.928 10.326 10.326 10.288 10.263 10.262 10.417 10.392 10.398 10.264 10.440 10.342 10.425 10.442 10.437 10.446 10.450 10.380
B3LYPultrafine   10.326     10.263 10.262 10.417 10.392     10.440 10.342 10.425   10.437 10.446    
B3PW91 9.122 10.518 10.518 10.451 10.433 10.430 10.554 10.533 10.536 10.428 10.570 10.491 10.555   10.558 10.571   10.509
mPW1PW91 9.112 10.505 10.505 10.438 10.417 10.413 10.538 10.511 10.514 10.410 10.554 10.474 10.536   10.540 10.554   10.476
M06-2X 8.892 10.306 10.306 10.230 10.240 10.227 10.360 10.375 10.375 10.244 10.392 10.287 10.398   10.374 10.413    
PBEPBE 9.003 10.432 10.432 10.395 10.383 10.380 10.546 10.505 10.507 10.380 10.562 10.460 10.541   10.558 10.570   10.488
PBEPBEultrafine   10.432     10.383 10.380 10.546 10.505     10.562 10.460 10.542   10.558 10.571    
PBE1PBE 9.048 10.467 10.467 10.410 10.390 10.390 10.513 10.484 10.487 10.383 10.527 10.448 10.511   10.516 10.529    
HSEh1PBE 9.039 10.464 10.464 10.402 10.380 10.376 10.504 10.476 10.479 10.374 10.520 10.438 10.504   10.507 10.522    
TPSSh   10.412 10.412 10.343 10.324 10.318 10.446 10.421   10.292 10.461 10.372 10.446   10.442 10.466    
wB97X-D     10.351   10.231   10.357   10.330   10.364 10.357 10.343     10.362    
B97D3   10.374     10.288       10.388             10.447    
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 cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z
Moller Plesset perturbation MP2 8.228 9.944 9.944 9.902 9.970 10.015 10.124 10.109 10.167 10.138 10.166 10.123 10.297 10.338 10.227 10.327 10.351 10.281
MP2=FULL 8.226 9.943 9.943 9.902 9.976 10.023 10.132 10.117 10.176 10.149 10.175 10.128 10.316 10.360 10.232 10.347 10.372  
ROMP2 8.115 9.879 9.879 9.840 9.939 9.991 10.106 10.086 10.152 10.127 10.151 10.104 10.293   10.216      
MP3         9.961   10.118       10.158 10.127 10.303          
MP3=FULL         9.968   10.126       10.167 10.132 10.324          
MP4   9.931     9.960       10.164   10.162 10.119 10.315   10.244 10.349    
MP4=FULL   9.932     9.968       10.173     10.124 10.336   10.248 10.371    
B2PLYP 8.603 10.108 10.108 10.069 10.070 10.084 10.219 10.197 10.221 10.126 10.248 10.172 10.282   10.269 10.307    
B2PLYP=FULL 8.602 10.108 10.108 10.069 10.073 10.086 10.222 10.200 10.223 10.129 10.251 10.174 10.288   10.270 10.312    
B2PLYP=FULLultrafine 8.647 10.051 10.051 9.998 9.954 9.950 10.071 10.051 10.056 9.945 10.089 10.013 10.071   10.079 10.085    
Configuration interaction CID   9.926 9.926 9.886 9.930     10.062                    
CISD   9.936 9.936 9.896 9.944     10.077                    
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 cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z
Quadratic configuration interaction QCISD   9.949 9.949 9.911 9.965 10.004 10.112 10.102 10.152 10.133 10.150 10.112 10.285   10.225 10.316   10.258
QCISD(T)         9.972     10.114     10.169 10.124 10.319   10.249 10.355   10.291
QCISD(T)=FULL         9.979   10.133         10.128 10.340 10.388 10.254 10.376 10.399  
QCISD(TQ)         9.972   10.127         10.126 10.321 10.367 10.252 10.357 10.379  
QCISD(TQ)=FULL         9.979   10.135         10.131 10.342 10.389 10.257 10.378 10.401  
Coupled Cluster CCD   9.936 9.936 9.900 9.948 9.987 10.093 10.084 10.135 10.114 10.130 10.096 10.264   10.205 10.293   10.243
CCSD         9.963         10.132 10.148 10.111 10.283 10.322 10.224 10.314 10.333  
CCSD=FULL         9.971         10.144 10.158 10.116 10.304 10.345 10.228 10.335 10.355  
CCSD(T)         9.971 10.013   10.113     10.168 10.123 10.318 10.365 10.248 10.354 10.377 10.291
CCSD(T)=FULL         9.978           10.178 10.128 10.339 10.387 10.253 10.375 10.399  
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 cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z

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 9.670 9.592 9.737 9.646 9.788 9.788
density functional B3LYP 10.259 10.224 10.323 10.285 10.446 10.433
Moller Plesset perturbation MP2 9.880 9.952 9.960 10.021 10.025 10.024
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.