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IV.D.1. (XII.C.1.)

Geometry Comparison

C3H4N2 (1H-Imidazole)


distance is atom 1 (N) to atom 5 (C)

Experimental bond length is 1.382  Å

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Calculated bond length in Å
Methods with predefined basis sets
semi-empirical PM3 1.393
PM6 1.336
composite G3 1.371
G3B3 1.379
G4 1.380
CBS-Q 1.372

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
hartree fock HF 1.411 1.394 1.394 1.386 1.371 1.371 1.371 1.371 1.371 1.372 1.370 1.331 1.372 1.370 1.374 1.371
density functional LSDA 1.420 1.388 1.388 1.384 1.365 1.365 1.366 1.362 1.362 1.363     1.365 1.361 1.366  
BLYP 1.453 1.416 1.416 1.411 1.391 1.390 1.391 1.388 1.388 1.389     1.390 1.385 1.391  
B1B95 1.422 1.396 1.396 1.390 1.369 1.370 1.371 1.368 1.368 1.369     1.370 1.366 1.370  
B3LYP 1.434 1.402 1.402 1.397 1.379 1.378   1.376   1.377 1.375 1.330 1.378 1.374    
B3LYPultrafine         1.379   1.379             1.378   1.379
B3PW91   1.398 1.398 1.393 1.374 1.373 1.374 1.371   1.373     1.374 1.370 1.375  
mPW1PW91   1.396   1.390 1.371 1.371 1.371 1.369 1.369 1.370     1.371   1.373  
M06-2X         1.329                      
PBEPBE   1.410     1.383 1.383 1.383 1.381 1.380 1.381 1.378   1.383 1.379    
PBEPBEultrafine         1.386                      
PBE1PBE         1.371                      
TPSSh         1.382   1.383             1.379    
Moller Plesset perturbation MP2   1.419 1.419 1.415 1.377 1.376 1.383 1.375 1.375 1.373   1.330 1.380      
MP2=FULL         1.375 1.375 1.376 1.374                
MP3         1.381   1.383                  
MP3=FULL         1.382   1.383                  
B2PLYP                           1.376    
B2PLYP=FULLultrafine         1.382                      
Configuration interaction CID         1.374                      
CISD         1.375                      
Quadratic configuration interaction QCISD   1.423     1.386       1.385              
Coupled Cluster CCD         1.382                      

Calculated bond length in Å
Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF 1.395 1.379 1.397 1.379 1.390 1.390
density functional B1B95 1.400 1.379        
B3LYP 1.410 1.388 1.410 1.388 1.400 1.400
Moller Plesset perturbation MP2 1.431 1.388 1.428 1.386 1.423 1.423
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
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