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Release 18October 2016
NIST Standard Reference Database 101
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III.G.1.a.

Comparison of levels of theory for S-S


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 1.9315
15
PM3 1.8882
13
PM6 1.9825
30
composite G2 1.9634
31
G3 1.9624
31
G3B3 2.0255
31
G3MP2 1.9402
3
G4 2.0104
30
CBS-Q 1.9653
21

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(D+d)Z cc-pV(T+d)Z aug-cc-pV(T+d)Z cc-pCVDZ cc-pCVTZ aug-cc-pCVTZ Sadlej_pVTZ
hartree fock HF 2.0340
28
2.1949
30
1.9881
31
2.1546
31
1.9971
31
1.9972
31
2.0103
25
2.0043
31
2.0135
28
1.9947
29
1.9926
16
2.0093
31
2.0117
31
1.9918
31
1.9035
11
2.0111
31
1.9935
30
1.9227
9
1.9560
9
1.9849
23
1.9505
12
1.9431
4
1.9368
6
2.0537
1
1.8992
1
ROHF   2.1691
6
1.9545
6
2.1536
4
1.9655
6
1.9655
6
1.9665
6
1.9720
6
1.9990
4
    2.0029
4
1.9774
6
1.9574
6
1.9742
2
2.0032
4
1.9828
4
1.9741
2
1.9481
3
1.9719
3
1.9648
1
  1.9719
2
   
density functional LSDA 2.0515
31
2.1032
31
1.9965
31
2.1603
31
2.0108
31
2.0109
31
2.0101
31
2.0128
31
2.0129
31
1.9907
31
  2.0482
9
2.0186
31
1.9947
31
  2.0168
31
1.9983
12
2.0007
1
1.9670
6
1.9891
8
1.9890
8
  1.9937
3
2.0400
1
 
SVWN   2.1843
31
    2.0196
28
2.0434
9
2.0099
31
2.0476
9
2.0485
9
2.0212
9
  2.0039
23
2.0498
9
2.0264
9
  2.0496
9
2.0261
9
  1.9649
4
1.9703
9
1.9890
8
  1.9937
3
2.0400
1
 
BLYP 2.0992
28
2.2466
31
2.0471
31
2.2169
31
1.9908
33
2.0624
30
2.0628
31
2.0697
31
2.0802
28
2.0294
19
  2.1078
9
2.0700
31
2.0461
31
  2.0963
14
2.0985
4
  1.9907
7
2.0207
9
2.0200
9
  2.0465
3
2.1000
1
 
B1B95 2.0522
29
2.1044
31
1.9926
31
2.1569
31
2.0038
31
2.0051
31
2.0051
30
2.0093
31
2.0150
29
1.9943
29
  2.0436
9
2.0138
31
1.9915
31
1.8988
4
2.0114
31
1.9788
18
1.8976
4
1.9452
7
1.9529
12
1.9526
12
1.9620
4
1.9464
6
2.0448
1
 
B3LYP 2.0748
28
2.2148
31
2.0182
31
2.1848
31
2.0327
31
2.0328
31
2.0324
31
2.0378
31
2.0279
17
2.0147
31
2.0421
12
2.0382
31
2.0934
31
2.0183
31
1.9440
11
2.0392
31
1.9912
30
1.9462
9
1.9808
9
2.0087
25
1.9755
12
1.9867
4
1.9695
6
2.0732
1
1.9415
1
B3LYPultrafine   2.2720
4
    2.0359
30
2.0822
4
2.0157
10
2.0909
4
      2.0897
4
2.0746
5
2.0361
19
  2.0754
5
2.0126
31
    2.0391
2
2.0398
2
  2.0205
3
2.0733
1
 
B3PW91 2.0669
25
2.2016
30
2.0028
31
2.1667
29
2.0156
31
2.0157
31
2.0153
31
2.0193
31
2.0094
17
1.9837
20
  2.0560
9
2.0244
31
2.0023
31
  2.0417
15
1.9856
3
  1.9541
7
1.9810
9
1.9809
9
  2.0042
3
2.0555
1
 
mPW1PW91 2.0607
25
2.1906
31
2.0071
29
2.1630
30
2.0108
31
2.0092
31
2.0088
31
2.0129
31
2.0224
28
1.9801
20
  2.0492
9
2.0178
31
1.9966
31
  2.0250
13
2.0296
9
  1.9493
7
1.9757
9
1.9756
9
  1.9985
3
2.0501
1
 
M06-2X 2.0620
9
2.2209
9
1.9673
33
2.1906
9
2.0078
31
2.0420
9
2.0423
9
2.0477
9
2.0485
9
2.0106
10
  2.0574
7
2.0498
9
2.0139
10
  2.0496
9
2.0135
10
  1.8606
3
1.9776
9
1.9774
9
  1.9991
3
2.0546
1
 
PBEPBE 2.0825
25
2.2027
22
2.0092
18
2.1780
18
2.0164
21
2.0165
21
2.0160
21
2.0206
21
2.0493
28
2.0232
28
2.0354
13
2.0747
9
2.0218
22
2.0016
21
1.9303
3
2.0460
12
2.0353
15
1.9283
3
1.9673
7
1.9780
12
1.9837
11
2.0088
3
1.9857
5
2.0675
1
1.9220
1
PBEPBEultrafine   2.2758
4
    2.0497
22
2.0823
4
2.0836
4
2.0909
4
      2.0880
4
2.0717
5
2.0506
5
  2.0731
5
2.0511
5
    2.0387
2
2.0397
2
  2.0194
3
2.0676
1
 
PBE1PBE 2.0707
5
2.0279
5
2.0279
5
2.1964
5
2.0022
27
2.0390
5
2.0404
5
2.0458
5
2.0472
5
2.0225
5
  2.0464
5
2.0475
5
2.0277
5
  2.0485
5
2.0281
5
    2.0353
6
2.0358
6
  1.9970
3
2.0481
1
 
HSEh1PBE 2.0704
9
2.1933
30
2.0302
9
2.1980
9
2.0154
29
2.0421
9
2.0148
29
2.0488
9
2.0500
9
2.0248
9
  2.0492
9
2.0504
9
2.0028
29
  2.0502
9
2.0295
9
  1.9089
4
1.9757
9
1.9756
9
  1.9984
3
2.0497
1
 
TPSSh 2.0900
2
2.2668
4
2.0594
4
2.2309
4
1.9771
31
2.0696
4
1.9770
31
2.0774
4
2.0617
2
1.9620
29
  2.0760
4
2.0777
4
1.9702
31
2.0337
2
2.0781
4
2.0561
4
2.0337
2
  2.0283
2
2.0293
2
  2.0301
2
2.0604
1
 
wB97X-D 2.0753
2
2.2190
2
1.9624
33
2.1815
2
1.9688
33
2.0401
2
1.9687
33
2.0463
2
1.9692
33
2.0254
2
  1.9712
33
1.9689
33
1.9623
33
2.0232
2
2.0510
2
1.9621
33
2.0232
2
  2.0182
2
2.0190
2
  2.0198
2
2.0555
1
 
B97D3 2.1100
2
2.0413
33
2.0559
2
2.2442
2
1.9801
33
2.0713
2
2.0729
2
2.0801
2
1.9813
33
2.0511
2
  2.0769
2
2.0757
2
2.0551
2
2.0476
2
2.0778
2
1.9726
33
2.0471
2
          2.0708
1
 
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(D+d)Z cc-pV(T+d)Z aug-cc-pV(T+d)Z cc-pCVDZ cc-pCVTZ aug-cc-pCVTZ Sadlej_pVTZ
Moller Plesset perturbation MP2 2.0729
25
2.2550
29
1.9971
31
2.2169
31
1.9723
31
2.0106
31
2.0103
31
1.9725
31
2.0191
29
1.9797
19
  2.0201
31
2.0292
31
1.9979
29
1.9491
8
2.0327
31
1.9836
20
1.9576
6
1.9712
9
1.9888
26
1.9738
10
1.9843
4
1.9583
6
2.0561
1
1.9278
1
MP2=FULL 2.0759
24
2.2534
30
2.0065
28
2.2280
28
2.0092
31
2.0091
31
2.0090
31
1.9930
23
2.0050
17
1.9813
17
  2.0504
9
2.0278
31
1.9984
29
1.9546
6
2.0076
16
1.9983
12
1.9565
4
1.9689
9
1.9818
26
1.9638
10
1.9825
4
1.9540
6
2.0515
1
1.9282
1
ROMP2 2.0526
4
1.9885
4
1.9885
4
2.1919
4
2.0030
4
2.0030
4
2.0032
4
2.0080
4
2.0082
4
1.9883
4
  2.0133
4
2.0187
4
1.9918
4
  2.0235
4
      1.9969
1
1.9978
1
  1.9738
2
   
MP3         2.0175
30
  1.9734
31
        2.0745
4
2.0828
4
2.0563
4
        1.9585
3
1.9586
4
1.9583
4
  2.0099
3
2.0668
1
 
MP3=FULL   2.2984
2
2.0326
2
2.2584
2
1.9728
31
2.0448
2
1.9726
31
2.0525
2
2.0524
2
2.0305
2
  2.0742
4
2.0817
4
2.0504
4
  2.0751
2
2.0332
2
    2.0232
2
2.0219
2
  2.0268
2
2.0633
1
 
MP4 2.1214
8
2.2744
28
    2.0241
31
    2.0139
2
2.0180
14
    2.0683
5
2.0746
5
1.9987
16
  2.0824
5
2.0478
5
  1.9771
7
1.9408
5
1.9397
5
  2.0160
3
2.0713
1
 
MP4=FULL   2.3013
5
    2.0526
5
      2.0641
5
      2.0732
5
2.0407
5
  2.0815
5
2.0387
5
    2.0296
2
2.0285
2
  2.0125
3
2.0674
1
 
B2PLYP 2.0961
4
2.2836
4
2.0558
4
2.2480
4
2.0176
26
2.0689
4
2.0144
6
2.0778
4
2.0196
6
2.0220
5
  2.0794
4
2.0818
4
1.9644
26
  2.0860
4
2.0267
5
  1.9741
2
2.0115
5
2.0116
5
  2.0335
2
2.0659
1
 
B2PLYP=FULL 2.0959
4
2.1692
6
2.0556
4
2.2482
4
2.0121
6
2.0684
4
2.0128
6
2.0777
4
2.0789
4
2.0516
4
  2.0791
4
2.0814
4
2.0572
4
  2.0857
4
2.0571
4
    2.0300
2
2.0305
2
  2.0324
2
2.0648
1
 
B2PLYP=FULLultrafine 2.0870
2
2.2765
2
2.0403
2
2.2364
2
2.0372
16
2.0534
2
2.0549
2
2.0617
2
2.0630
2
2.0370
2
  2.0634
2
2.0655
2
2.0420
2
  2.0709
2
2.0424
2
    2.0301
2
2.0305
2
  2.0324
2
2.0648
1
 
Configuration interaction CID 2.1038
8
2.2348
27
1.9839
19
2.1837
19
2.0033
31
2.0535
1
  1.9944
20
        2.0749
1
          1.8197
1
1.9469
3
1.9469
3
  2.0006
3
2.0557
1
 
CISD 2.1039
8
2.2393
27
1.9821
18
2.1856
18
2.0541
31
2.0640
2
  1.9976
18
        2.0753
1
          1.8218
1
1.9482
3
1.9482
3
  2.0125
2
2.0563
1
 
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(D+d)Z cc-pV(T+d)Z aug-cc-pV(T+d)Z cc-pCVDZ cc-pCVTZ aug-cc-pCVTZ Sadlej_pVTZ
Quadratic configuration interaction QCISD 2.1214
10
2.2808
30
2.0166
28
2.2413
28
2.0692
31
2.0294
28
2.0194
31
2.0251
31
2.0192
19
2.0090
15
  2.0648
9
2.0169
22
1.9958
19
  2.0769
9
2.0263
10
  1.9802
9
1.9742
14
1.9905
9
  2.0131
3
2.0669
1
 
QCISD(T)         2.0246
30
1.9591
2
1.9593
2
1.9966
5
2.0909
2
    2.0724
9
2.0398
14
2.0111
14
  2.0455
14
2.0220
12
  2.0090
3
2.0273
7
2.0278
7
  2.0196
3
2.0731
1
 
QCISD(T)=FULL         2.0687
4
  2.0707
4
          2.0907
4
2.0570
4
2.0300
2
2.0993
4
2.0555
4
2.0307
2
  2.0297
2
2.0289
2
  2.0345
2
2.0691
1
 
QCISD(TQ)         2.0563
2
  2.0582
2
          2.0769
2
2.0499
2
2.0014
1
2.0869
2
                 
QCISD(TQ)=FULL         2.0550
2
  2.0571
2
          2.0757
2
2.0435
2
  2.0862
2
                 
Coupled Cluster CCD 2.1198
10
2.2615
28
2.0122
28
2.2264
28
2.0146
31
2.0252
28
2.0254
28
2.0264
29
2.0314
14
2.0138
14
  2.0593
9
2.0191
20
2.0044
16
  2.0406
12
2.0077
12
  1.9758
9
1.9700
14
1.9662
12
1.9425
2
1.9681
5
2.0655
1
 
CCSD   2.1739
2
    1.9931
22
1.9386
2
1.9384
2
1.9715
4
2.0831
2
2.0193
5
  2.0645
5
2.0361
12
1.9988
13
2.0078
3
2.0777
5
2.0164
6
2.0079
3
1.9995
3
2.0249
7
1.9995
8
  2.0120
3
2.0668
1
 
CCSD=FULL         2.0026
7
        2.0121
5
  2.0636
5
2.0403
6
1.9915
7
2.0040
3
2.0467
6
1.9887
7
2.0038
3
  1.9685
3
1.9661
3
  2.0075
3
2.0620
1
 
CCSD(T)   2.2196
2
    2.0291
28
1.9730
7
2.0070
4
1.9952
5
2.0780
4
2.0443
2
1.9040
1
2.0714
9
2.0200
17
1.9878
19
1.9901
4
2.0247
17
1.9979
10
2.0151
3
2.0064
5
1.9953
10
2.0057
9
1.9944
4
1.9706
6
2.0730
1
 
CCSD(T)=FULL         2.0209
13
            2.0706
9
2.0625
10
2.0296
10
1.9866
4
2.0697
10
2.0270
10
2.0111
3
1.9864
7
1.9714
12
1.9924
10
1.9921
4
1.9668
6
2.0690
1
 
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(D+d)Z cc-pV(T+d)Z aug-cc-pV(T+d)Z cc-pCVDZ cc-pCVTZ aug-cc-pCVTZ Sadlej_pVTZ

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 2.1509
31
2.0112
31
2.1522
31
2.0099
31
2.1803
30
2.1829
30
density functional B1B95 2.1895
18
2.0465
18
2.2355
2
2.0865
2
2.2615
2
2.2448
2
B3LYP 2.1958
31
2.0487
31
2.1938
31
2.0458
31
2.2246
30
2.2111
31
wB97X-D 2.1926
2
2.0558
2
2.1939
2
2.0549
2
2.2163
2
2.2122
2
Moller Plesset perturbation MP2 2.2165
31
2.0295
31
2.2158
31
2.0258
31
2.2424
30
2.2407
30
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.