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III.G.1.a.

Comparison of levels of theory for Be-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 1.8712
2
PM3 1.7646
3
PM6 1.8316
3
composite G2 1.7981
3
G3 1.7981
3
G3B3 1.8075
3
G4 1.8037
3
CBS-Q 1.8001
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 1.7464
2
1.8282
3
1.8062
3
1.8354
3
1.7981
6
1.7981
3
1.7972
3
1.7941
3
1.7941
3
1.7962
3
1.7251
1
1.8070
3
1.7994
3
1.8236
2
1.7249
1
1.8344
2
1.7933
3
1.7675
2
1.7264
1
ROHF         1.8393
1
                           
density functional LSDA 1.7380
3
1.8143
3
1.8099
3
1.8329
3
1.8029
3
1.8029
3
1.8004
3
1.7931
3
1.7931
3
1.7990
3
    1.8064
3
1.7903
3
  1.8040
3
1.8169
2
   
SVWN   1.8256
3
    1.8028
3
  1.8004
3
                       
BLYP 1.7824
2
1.8448
3
1.8283
3
1.8534
3
1.8227
3
1.8227
3
1.8206
3
1.8143
3
1.8143
3
1.8191
3
    1.8245
3
1.8373
2
  1.7680
1
     
B1B95 1.7352
3
1.8150
3
1.8099
3
1.8346
3
1.8019
3
1.8027
3
1.8007
3
1.7964
3
1.7964
3
1.8004
3
    1.8060
3
1.7927
3
  1.8047
3
     
B3LYP 1.7388
3
1.8316
3
1.8139
3
1.8397
3
1.8077
3
1.8077
3
1.8056
3
1.8004
3
1.8291
2
1.8043
3
1.7388
1
1.8157
3
1.8095
3
1.8249
2
1.7375
1
1.8378
2
1.7979
3
1.7379
1
1.7396
1
B3LYPultrafine         1.8078
3
                      1.7980
3
   
B3PW91 1.7661
2
1.8315
3
1.8139
3
1.8379
3
1.8051
3
1.8051
3
1.8035
3
1.7993
3
1.8280
2
1.8023
3
    1.8362
2
1.8244
2
  1.7507
1
     
mPW1PW91 1.7295
3
1.8291
3
1.8413
2
1.8354
3
1.8026
3
1.8026
3
1.8008
3
1.7969
3
1.7969
3
1.8003
3
    1.8341
2
1.8225
2
  1.7478
1
     
M06-2X         1.7983
3
                           
PBEPBE 1.7773
2
1.8419
3
1.8544
2
1.8790
2
1.8176
3
1.8176
3
1.8152
3
1.8107
3
1.8107
3
1.8146
3
1.7514
1
  1.8208
3
1.8075
3
        1.7521
1
PBEPBEultrafine         1.7624
1
                           
PBE1PBE         1.8031
3
                           
HSEh1PBE         1.8038
3
                           
TPSSh         1.7938
3
  1.7919
3
            1.7859
3
         
Moller Plesset perturbation MP2 1.7613
2
1.8479
3
1.8208
3
1.8561
3
1.8032
3
1.8032
3
1.8025
3
1.8018
3
1.8018
3
1.8095
3
  1.8226
3
1.8186
3
1.8327
2
1.7524
1
1.8269
3
1.8110
3
1.7533
1
1.7573
1
MP2=FULL 1.7609
2
1.8478
3
1.8459
2
1.8836
2
1.7994
3
1.7994
3
1.7986
3
1.8003
3
1.8249
2
1.8258
2
    1.8402
2
1.8209
2
1.7438
1
1.7726
1
    1.7456
1
MP3         1.7956
3
  1.7856
3
                       
MP3=FULL         1.7828
3
  1.7816
3
                       
MP4   1.8847
2
    1.8119
3
    1.7683
1
1.8321
2
        1.8150
3
         
B2PLYP         1.8066
3
                1.7867
3
         
Configuration interaction CID   1.8724
2
1.8427
2
1.8831
2
1.7955
3
    1.7941
3
                     
CISD   1.8783
2
1.8467
2
1.8890
2
1.7997
3
    1.8256
2
                     
Quadratic configuration interaction QCISD   1.8585
3
1.8525
2
1.8964
2
1.8068
3
1.8317
2
1.8059
3
1.8056
3
1.8057
3
1.8360
2
    1.8218
3
1.8063
3
        1.7518
1
QCISD(T)         1.8119
3
    1.7636
1
        1.8520
2
1.8375
2
  1.8600
2
1.8410
2
   
Coupled Cluster CCD   1.8742
2
1.8445
2
1.8851
2
1.7975
3
1.8248
2
1.8234
2
1.7964
3
1.8238
2
1.8313
2
    1.8129
3
1.8279
2
  1.8491
2
1.8314
2
   
CCSD         1.8021
3
    1.7470
1
                     
CCSD(T)   1.8008
1
    1.7598
1
1.7598
1
1.7598
1
1.7588
1
1.7588
1
  1.7570
1
  1.8257
3
1.8112
3
  1.8324
3
1.8139
3
  1.7595
1
CCSD(T)=FULL         1.8300
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 1.8435
3
1.8069
3
1.8377
3
1.7968
3
1.8416
3
1.8304
3
density functional B1B95 1.7925
1
1.7702
1
       
B3LYP 1.8598
3
1.8249
3
1.8534
3
1.8154
3
1.8538
3
1.8353
3
Moller Plesset perturbation MP2 1.8781
3
1.8241
3
1.8597
3
1.8102
3
1.8618
3
1.8469
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.