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III.G.1.a.

Comparison of levels of theory for S-Se


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 2.9341
1
PM3 2.0413
2
PM6 1.8963
3
composite G2 2.0241
3
G3B3 2.0962
3
G4 2.0812
3
CBS-Q 2.0316
2

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) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ
hartree fock HF 2.0586
3
2.2338
2
2.0225
3
2.0618
2
2.0241
6
2.0241
3
2.0219
3
2.0305
3
2.0305
3
2.0024
3
2.0309
3
2.0297
3
2.0197
3
2.0219
2
2.0319
3
2.0192
3
2.0210
2
density functional LSDA 2.0920
3
2.1005
3
2.0541
3
2.1625
3
2.0621
3
2.0621
3
2.0579
3
2.0133
2
2.0133
2
2.0377
2
  2.0676
3
2.0513
3
  2.0659
3
1.9671
1
2.0516
2
SVWN   2.1939
3
    2.0497
1
  2.0579
3
                   
BLYP 2.1245
3
2.1898
2
2.0468
2
2.2163
3
2.1105
3
2.1105
3
2.1530
2
2.1011
1
2.1011
1
2.0771
3
  2.1165
3
2.1004
3
  2.1005
1
   
B1B95 2.0804
3
2.0918
3
2.0454
3
2.1514
3
2.0501
3
2.0501
3
2.0461
3
2.0564
3
2.0564
3
2.0243
3
  2.0560
3
2.0433
3
2.0447
2
2.0551
3
2.0467
2
2.1354
1
B3LYP 2.0981
3
2.2108
3
2.0695
3
2.1796
3
2.0776
3
2.0776
3
2.0738
3
2.0834
3
2.0834
3
2.0479
3
2.0822
3
2.0832
3
2.0683
3
2.0712
2
2.0819
3
2.0667
3
2.0693
2
B3LYPultrafine         2.0842
2
                    2.0773
3
 
B3PW91 2.0900
3
2.1978
3
2.0562
3
2.1629
3
2.0611
3
2.0611
3
2.0572
3
2.0663
3
2.0663
3
2.0335
3
  2.0668
3
2.0528
3
  2.0536
1
   
mPW1PW91 2.0840
3
2.1912
3
2.0497
3
2.1550
3
2.0538
3
2.0538
3
2.0501
3
2.0591
3
2.0591
3
2.0271
3
  2.0594
3
2.0461
3
  2.0468
1
   
M06-2X         2.0460
3
                       
PBEPBE 2.1089
3
2.2241
3
2.0778
3
2.1352
2
2.1298
2
2.1298
2
2.0801
3
2.0911
3
2.0911
3
2.0541
3
  2.0901
3
2.0758
3
2.0791
2
2.0757
1
  2.0769
2
PBE1PBE         2.0526
3
                       
HSEh1PBE         2.0554
3
                       
TPSSh         2.0646
3
  2.0614
3
          2.0560
3
       
Moller Plesset perturbation MP2 2.1276
3
2.3079
3
2.0660
3
2.2745
3
2.0767
3
2.0767
3
2.0769
3
2.0833
3
2.0833
3
2.0485
3
2.0804
3
2.0829
3
2.0615
3
  2.0899
3
2.0956
2
 
MP2=FULL 2.1275
3
2.3089
3
2.0651
3
2.2756
3
2.0736
3
2.0736
3
2.0737
3
2.0811
3
2.0811
3
2.0349
3
  2.0818
3
2.0568
3
       
MP3         2.0722
2
  2.0642
3
                   
MP3=FULL         2.0615
3
  2.0596
3
                   
MP4 2.0869
1
2.2518
2
    2.0859
3
      2.1935
1
      2.0818
2
       
B2PLYP         2.0809
3
              2.0700
3
       
Configuration interaction CID 2.0732
1
2.2297
3
2.0469
3
2.1929
3
2.0549
3
    2.0593
3
2.0451
1
               
CISD 2.0855
1
2.2346
3
2.0498
3
2.1970
3
2.0578
3
    2.0625
3
2.0479
1
               
Quadratic configuration interaction QCISD 2.0931
1
2.2605
3
2.0657
3
2.2182
3
2.0744
3
2.0744
3
2.0715
3
2.1254
2
2.1254
2
2.0403
3
  2.0884
2
2.0633
2
       
QCISD(T) 2.0929
1
      2.0867
3
  2.0667
1
2.0740
1
      2.0920
3
2.1090
2
  2.0976
3
2.0770
2
 
Coupled Cluster CCD 2.0766
1
2.2463
3
2.0565
3
2.2104
3
2.0655
3
2.0655
3
2.0650
3
2.0707
3
2.0707
3
2.0358
3
  2.1715
1
2.0559
2
  2.0835
2
2.1463
1
 
CCSD         2.0724
3
  2.0542
1
2.0598
1
      2.0587
1
2.0370
1
  2.0651
1
   
CCSD(T) 2.0932
1
      2.0677
1
  2.0658
1
2.0728
1
      2.0906
3
2.0678
3
  2.0963
3
2.0759
2
 
CCSD(T)=FULL         2.0906
2
            2.0699
1
2.0458
1
       

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 2.1520
3
  2.1517
3
  2.1853
3
2.3439
3
density functional B3LYP 2.2021
3
  2.2019
3
  2.2271
3
2.2075
3
Moller Plesset perturbation MP2 2.2451
3
  2.2894
3
  2.3219
3
2.2664
3
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.