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

Geometry Comparison

C4 (Carbon tetramer)


distance is atom 1 (C) to atom 3 (C)

Experimental bond length is 1.304  Å

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Calculated bond length in Å
Methods with predefined basis sets
semi-empirical PM3 1.190
PM6 1.201
composite G2 1.299
G3 1.299
G3B3 1.315
G4 1.311
CBS-Q 1.303

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 1.314 1.305 1.305 1.311 1.299 1.299 1.299 1.297 1.297 1.297 1.291 1.292 1.305 1.294 1.305  
ROHF   1.297 1.297 1.303 1.292 1.292 1.292 1.289         1.297 1.287    
density functional LSDA 1.324 1.309 1.309 1.319 1.310 1.310 1.311 1.301 1.301 1.305     1.314 1.298 1.313  
SVWN   1.326     1.318   1.317                  
BLYP 1.361 1.336 1.336 1.340 1.328 1.328 1.326 1.322 1.322 1.323     1.331 1.317    
B1B95 1.347 1.322 1.322 1.326 1.312 1.314 1.314 1.309 1.309 1.310     1.317 1.304 1.316  
B3LYP 1.351 1.323 1.323 1.327 1.315 1.315 1.314 1.309 1.309 1.310   1.305 1.319 1.305 1.318 1.306
B3LYPultrafine                               1.306
B3PW91 1.350 1.325 1.325 1.329 1.316 1.316 1.315 1.311 1.311 1.313     1.320 1.308    
mPW1PW91 1.346 1.323 1.323 1.326 1.314 1.314 1.313 1.309 1.309 1.311     1.318 1.306    
M06-2X         1.313                      
PBEPBE 1.355 1.335 1.335 1.339 1.329 1.329 1.328 1.323 1.323 1.325     1.332 1.320    
PBEPBEultrafine         1.329                      
PBE1PBE         1.315                      
HSEh1PBE         1.315                      
TPSSh         1.315   1.314             1.307    
Moller Plesset perturbation MP2 1.349 1.329 1.330 1.338 1.314 1.314 1.314 1.314 1.314 1.309   1.306 1.326 1.308 1.327  
MP2=FULL 1.348 1.330 1.330 1.337 1.313 1.313 1.313 1.313 1.313 1.305     1.325 1.302 1.332  
MP3             1.308                  
MP3=FULL         1.306   1.306                  
MP4 1.354 1.336     1.321       1.322 1.315       1.314    
B2PLYP         1.315                 1.303    
Configuration interaction CID 1.341 1.321 1.321 1.328 1.307     1.306 1.306 1.301            
CISD 1.343 1.323 1.323 1.330 1.308     1.307 1.307 1.302            
Quadratic configuration interaction QCISD   1.329 1.329 1.339 1.319 1.319 1.319 1.319 1.319 1.313     1.331 1.312    
QCISD(T)         1.325                      
Coupled Cluster CCD 1.349 1.328 1.328 1.336 1.313 1.313 1.313 1.313 1.313 1.308     1.325 1.306    
CCSD(T)         1.323                 1.317    

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 1.344 1.330 1.323 1.305 1.320 1.320
density functional B1B95 1.363 1.350        
B3LYP 1.366 1.350 1.344 1.323 1.341 1.342
Moller Plesset perturbation MP2 1.380 1.350 1.356 1.323 1.354 1.353
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
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