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III.G.1.a.

Comparison of levels of theory for Si-N


Click on an entry for a histogram of the values.
The subscript refers to how many bonds of that type have been calculated.
average calculated bond lengths (Å)
Methods with predefined basis sets
semi-empirical AM1 1.5146
1
PM3 1.5335
3
PM6 1.5994
3
composite G2 1.6155
3
G3 1.6155
3
G3B3 1.6178
3
CBS-Q 1.6171
3
average calculated bond lengths (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 cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z
hartree fock HF 1.8598
2		 1.9767
3		 1.8240
3		 2.0836
3		 1.6464
2		 1.6155
3		 1.6183
3		 1.6128
3		 1.6128
3		 1.6013
3		 1.5715
1		 1.7544
3		 1.8729
3		 1.6104
3		 1.6027
3		 1.8211
3		 1.6118
3		 1.6034
3		 1.5748
1
ROHF   1.5889
1		 1.5438
1		   1.5400
1		 1.5400
1		 1.5425
1		 1.5370
1		         1.5537
1		 1.5403
1		          
density functional LSDA 1.6175
3		 1.6362
3		 1.6215
3		 1.6766
3		 1.6138
3		 1.6138
3		 1.6143
3		 1.6092
3		 1.6092
3		 1.6035
3		     1.6263
3		 1.6074
3		 1.6205
2		 1.6284
3		 1.6273
2		 1.6205
2		  
SVWN   1.6697
3		     1.6139
3		   1.6144
3		                        
BLYP 1.6620
2		 1.6894
3		 1.6421
3		 1.6994
3		 1.6349
3		 1.6349
3		 1.6359
3		 1.6311
3		 1.6310
3		 1.6241
3		     1.6468
3		 1.6287
3		   1.6071
1		      
B1B95 1.6084
3		 1.6347
3		 1.6195
3		 1.6786
3		 1.6105
3		 1.6111
3		 1.6120
3		 1.6077
3		 1.6077
3		 1.6027
3		     1.6247
3		 1.6072
3		 1.6214
2		 1.5919
2		 1.5833
1		 1.6217
2		  
B3LYP 1.6153
3		 1.6750
3		 1.6256
3		 1.6843
3		 1.6178
3		 1.6178
3		 1.6191
3		 1.6142
3		 1.6345
2		 1.6080
3		 1.5660
1		 1.6227
3		 1.6305
3		 1.6129
3		 1.6073
3		 1.6336
3		 1.6140
3		 1.6076
3		 1.5664
1
B3LYPultrafine         1.6178
3		                            
B3PW91 1.6411
2		 1.6748
3		 1.6246
3		 1.6827
3		 1.6155
3		 1.6155
3		 1.6162
3		 1.6118
3		 1.6322
2		 1.6066
3		     1.6288
3		 1.6112
3		   1.5898
1		      
mPW1PW91 1.6019
3		 1.6723
3		 1.6430
2		 1.6804
3		 1.6122
3		 1.6122
3		 1.6130
3		 1.6088
3		 1.6088
3		 1.6036
3		     1.6258
3		 1.6084
3		   1.5875
1		      
M06-2X         1.6077
3		                            
PBEPBE 1.6574
2		 1.6875
3		 1.6613
2		 1.7216
2		 1.6307
3		 1.6307
3		 1.6310
3		 1.6269
3		 1.6269
3		 1.6211
3		 1.5782
1		   1.6437
3		 1.6254
3		 1.6396
2		   1.5858
1		 1.6398
2		 1.5787
1
PBEPBEultrafine         1.5899
1		                            
HSEh1PBE         1.6138
3		                            
Moller Plesset perturbation MP2FC 1.6539
2		 1.6705
3		 1.6218
3		 1.6773
3		 1.6138
3		 1.6138
3		 1.6134
3		 1.6074
3		 1.6073
3		 1.6052
3		   1.6155
3		 1.6261
3		 1.6072
3		 1.6006
3		 1.6310
3		 1.6096
3		 1.6016
3		 1.5274
1
MP2FU 1.6534
2		 1.6707
3		 1.6615
2		 1.7220
2		 1.6128
3		 1.6128
3		 1.6125
3		 1.6066
3		 1.6444
2		 1.6393
2		     1.6254
3		 1.6412
2		 1.5944
3		 1.5499
1		   1.6307
2		 1.5235
1
MP3         1.5970
3		                            
MP4   1.7152
2		     1.6234
3		     1.5439
1		 1.6545
2		         1.6203
3		          
B2PLYP         1.6237
3		   1.6252
3		                        
Configuration interaction CID   1.6822
2		 1.6332
2		 1.6995
2		 1.5994
3		     1.5934
3		                      
CISD   1.7098
2		 1.6411
2		 1.7274
2		 1.6090
3		     1.6262
2		                      
Quadratic configuration interaction QCISD   1.7037
3		 1.6570
2		 1.7427
2		 1.6265
3		 1.6471
2		 1.6274
3		 1.6198
3		 1.6198
3		 1.6359
2		     1.6440
3		 1.6193
3		         1.5720
1
QCISD(T)         1.6338
3		     1.5839
1		         1.6755
2		 1.6495
2		   1.6829
2		 1.6518
2		    
Coupled Cluster CCD   1.6860
2		 1.6392
2		 1.6958
2		 1.6319
2		 1.6319
2		 1.6319
2		 1.5963
3		 1.6252
2		 1.6231
2		     1.6160
3		 1.6253
2		   1.6506
2		 1.6275
2		    
CCSD         1.6242
3		                            
CCSD(T)   1.6514
1		     1.5861
1		 1.5864
1		 1.5875
1		 1.5795
1		 1.5794
1		   1.5733
1		   1.6726
2		 1.6249
3		   1.6803
2		 1.6491
2		   1.5753
1
CCSD(T)=FULL         1.6513
2		                            
average calculated bond lengths (Å)
Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF 2.2467
2		 1.6652
2		 2.2440
2		 1.8210
2		 2.1775
2		 2.2724
2
density functional B1B95 1.6298
1		 1.5868
1		        
B3LYP 1.7108
2		 1.6446
2		 1.7109
2		 1.6487
2		 1.6796
2		 1.6945
2
Moller Plesset perturbation MP2FC 1.7315
2		 1.6528
2		 1.7231
2		 1.6553
2		 1.6935
2		 1.7044
2
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.