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Geometry Comparison

C4H4N2 (1,3-Diazine)


distance is atom 3 (C) to atom 5 (N)

Experimental bond length is 1.350  Å

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Calculated bond length in Å
Methods with predefined basis sets
semi-empirical PM3 1.354
PM6 1.364
composite G2 1.321
G3 1.321
G3B3 1.339
G4 1.334

Calculated bond length in Å
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 cc-pVDZ cc-pVTZ aug-cc-pVDZ aug-cc-pVTZ daug-cc-pVTZ
hartree fock HF 1.354 1.332 1.332 1.333 1.316 1.321 1.316 1.319 1.319 1.318 1.317 1.313 1.322 1.317 1.323 1.317 1.317
density functional BLYP 1.411 1.367   1.367 1.349 1.352 1.353   1.349 1.348     1.353 1.346 1.353    
B1B95 1.382 1.348 1.348 1.348 1.332 1.333 1.334 1.330 1.330 1.330     1.334 1.326 1.332    
B3LYP 1.391 1.352 1.352 1.354 1.339 1.339 1.340 1.336   1.335 1.333 1.329 1.340 1.333   1.334  
B3LYPultrafine         1.339   1.340             1.328   1.332  
B3PW91   1.351 1.351 1.351 1.336 1.336   1.333   1.333     1.337 1.330 1.337    
mPW1PW91   1.348   1.348 1.333 1.333 1.334 1.330 1.331 1.331     1.334   1.334    
M06-2X     1.350   1.329                        
PBEPBE   1.363     1.347 1.347 1.348 1.344 1.344 1.344 1.341   1.347 1.341      
PBEPBEultrafine         1.339                        
PBE1PBE         1.334                        
HSEh1PBE   1.340     1.328   1.329             1.323      
TPSSh         1.340   1.341     1.338       1.334      
wB97X-D     1.349   1.335   1.336   1.332     1.330 1.336 1.330   1.330  
B97D3   1.361     1.345   1.347   1.343   1.340 1.341   1.340   1.340  
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 cc-pVDZ cc-pVTZ aug-cc-pVDZ aug-cc-pVTZ daug-cc-pVTZ
Moller Plesset perturbation MP2   1.370 1.370 1.372 1.343 1.343 1.338 1.341 1.342 1.339   1.333 1.348 1.338      
MP2=FULL         1.342     1.341                  
MP3         1.339   1.338                    
MP3=FULL         1.337   1.338                    
B2PLYP         1.334                 1.335      
B2PLYP=FULLultrafine         1.334                        
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 cc-pVDZ cc-pVTZ aug-cc-pVDZ aug-cc-pVTZ daug-cc-pVTZ
Quadratic configuration interaction QCISD                 1.340                
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 cc-pVDZ cc-pVTZ aug-cc-pVDZ aug-cc-pVTZ daug-cc-pVTZ

Calculated bond length in Å
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 1.347 1.331 1.345 1.327 1.339 1.339     1.316
density functional B1B95 1.363 1.345              
B3LYP 1.370 1.351 1.367 1.347 1.359 1.360     1.334
PBEPBE                 1.341
Moller Plesset perturbation MP2 1.393 1.357 1.387 1.353 1.383 1.383     1.338
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
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