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Comparison of levels of theory for C-Be


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 1.6185
2
PM3 1.5772
2
PM6 1.6708
2
composite G2 1.6460
2
G3 1.6460
2
G3B3 1.6513
2
G4 1.6492
2
CBS-Q 1.6465
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) 6-311+G(3df,2p) TZVP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ daug-cc-pVTZ
hartree fock HF 1.6004
2
1.6752
2
1.6752
2
1.6613
2
1.6433
2
1.6464
2
1.6489
2
1.6424
2
1.6424
2
1.6419
2
  1.6608
2
1.6493
2
1.6437
2
1.6398
2
1.6485
2
1.6434
2
1.6400
2
1.6576
1
ROHF   1.8073
2
1.8073
2
1.7964
2
1.6972
2
1.6972
2
1.6907
2
1.6815
2
1.6815
2
    1.7141
2
1.6952
2
1.6817
2
1.6753
2
1.6894
2
1.6798
2
1.6751
2
 
density functional LSDA 1.6192
2
1.6743
2
1.6743
2
1.6611
2
1.6466
2
1.6466
2
1.6489
2
1.6404
2
1.6404
2
1.6438
2
  1.6589
2
1.6512
2
1.6418
2
  1.6503
2
1.6416
2
   
BLYP 1.6430
2
1.6881
2
1.6881
2
1.6765
2
1.6621
2
1.6621
2
1.6654
2
1.6571
2
1.6571
2
1.6600
2
  1.6774
2
1.6654
2
1.6583
2
         
B1B95 1.6273
2
1.6813
2
1.6813
2
1.6685
2
1.6534
2
1.6534
2
1.6543
2
1.6479
2
1.6479
2
1.6508
2
  1.6641
2
1.6562
2
1.6497
2
  1.6739
1
1.6496
2
   
B3LYP 1.6314
2
1.6815
2
1.6815
2
1.6696
2
1.6541
2
1.6541
2
1.6558
2
1.6482
2
1.6482
2
1.6517
2
  1.6656
2
1.6566
2
1.6500
2
1.6459
2
1.6573
2
1.6499
2
1.6463
2
 
B3LYPultrafine   1.6815
2
    1.6541
2
1.6541
2
1.6558
2
1.6482
2
      1.6656
2
1.6566
2
1.6500
2
  1.6573
2
1.6499
2
   
B3PW91 1.6301
2
1.6848
2
1.6848
2
1.6719
2
1.6561
2
1.6561
2
1.6572
2
1.6504
2
1.6504
2
1.6535
2
  1.6668
2
1.6588
2
1.6520
2
         
mPW1PW91 1.6272
2
1.6836
2
1.6836
2
1.6707
2
1.6543
2
1.6543
2
1.6554
2
1.6488
2
1.6488
2
1.6518
2
  1.6653
2
1.6570
2
1.6504
2
  1.6577
2
1.6504
2
   
M06-2X 1.6048
2
1.6740
2
1.6740
2
1.6604
2
1.6444
2
1.6444
2
1.6432
2
1.6436
2
1.6436
2
1.6450
2
1.6413
2
1.6568
2
1.6512
2
1.6435
2
  1.6449
2
1.6431
2
   
PBEPBE 1.6389
2
1.6882
2
1.6882
2
1.6757
2
1.6614
2
1.6614
2
1.6639
2
1.6564
2
1.6564
2
1.6602
2
  1.6744
2
1.6653
2
1.6584
2
  1.6657
2
1.6586
2
   
PBEPBEultrafine   1.6882
2
    1.6614
2
1.6614
2
1.6640
2
1.6564
2
      1.6744
2
1.6653
2
1.6584
2
  1.6657
2
1.6586
2
   
PBE1PBE 1.6262
2
1.6838
2
1.6838
2
1.6709
2
1.6545
2
1.6545
2
1.6556
2
1.6489
2
1.6489
2
1.6519
2
  1.6656
2
1.6572
2
1.6507
2
  1.6578
2
1.6507
2
   
HSEh1PBE 1.6271
2
1.6843
2
1.6843
2
1.6713
2
1.6547
2
1.6547
2
1.6559
2
1.6492
2
1.6492
2
1.6521
2
  1.6661
2
1.6547
2
1.6510
2
  1.6582
2
1.6509
2
   
TPSSh   1.6926
2
1.6926
2
1.6783
2
1.6627
2
1.6627
2
1.6638
2
1.6575
2
      1.6730
2
1.6653
2
1.6591
2
  1.6655
2
1.6590
2
   
wB97X-D     1.6944
1
  1.6656
1
  1.6643
1
  1.6583
1
    1.6710
1
1.6643
1
1.6600
1
    1.6598
1
   
B97D3   1.7103
1
    1.6823
1
  1.6843
1
  1.6791
1
  1.6771
1
1.7042
1
  1.6789
1
    1.6853
1
  1.6700
2
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 daug-cc-pVTZ
Moller Plesset perturbation MP2 1.6077
2
1.6836
2
1.6836
2
1.6728
2
  1.6464
2
1.6506
2
  1.6514
2
1.6486
2
  1.6684
2
1.6625
2
1.6532
2
1.6468
2
1.6663
2
1.6541
2
1.6478
2
 
MP2=FULL 1.6074
2
1.6832
2
1.6832
2
1.6724
2
1.6436
2
1.6436
2
1.6476
2
1.6486
2
1.6486
2
1.6391
2
  1.6672
2
1.6605
2
1.6370
2
1.6377
2
1.6604
2
1.6346
2
1.6389
2
 
ROMP2 1.5975
2
1.6765
2
1.6765
2
1.6662
2
1.6438
2
1.6438
2
1.6484
2
1.6492
2
1.6492
2
1.6435
2
  1.6631
2
1.6584
2
1.6485
2
  1.6623
2
     
MP3         1.6451
2
  1.6494
2
        1.6688
2
1.6642
2
1.6538
2
         
MP3=FULL         1.6423
2
  1.6461
2
        1.6677
2
1.6623
2
1.6330
2
         
MP4   1.6884
2
    1.6473
2
      1.6545
2
    1.6717
2
1.6666
2
1.6563
2
  1.6721
2
1.6576
2
   
MP4=FULL   1.6881
2
    1.6443
2
      1.6517
2
      1.6646
2
1.6350
2
  1.6661
2
1.6359
2
   
B2PLYP 1.6126
2
1.6815
2
1.6815
2
1.6697
2
1.6505
2
1.6505
2
1.6527
2
1.6482
2
1.6482
2
1.6484
2
  1.6672
2
1.6568
2
1.6501
2
  1.6589
2
1.6506
2
   
B2PLYP=FULL 1.6126
2
1.6814
2
1.6814
2
1.6696
2
1.6496
2
1.6496
2
1.6517
2
1.6473
2
1.6473
2
1.6456
2
  1.6669
2
1.6562
2
1.6444
2
  1.6571
2
1.6448
2
   
B2PLYP=FULLultrafine         1.6496
2
              1.6562
2
1.6444
2
    1.6448
2
   
Configuration interaction CID   1.6850
2
1.6850
2
1.6754
2
1.6443
2
    1.6510
2
                     
CISD   1.6901
2
1.6901
2
1.6803
2
1.6470
2
    1.6533
2
                     
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 daug-cc-pVTZ
Quadratic configuration interaction QCISD   1.6933
2
1.6933
2
1.6839
2
1.6494
2
1.6494
2
1.6534
2
1.6557
2
1.6557
2
1.6523
2
  1.6729
2
1.6676
2
1.6565
2
  1.6724
2
1.6574
2
   
QCISD(T)         1.6528
2
            1.6775
2
1.6717
2
1.6609
2
  1.6771
2
1.6622
2
   
QCISD(T)=FULL         1.6498
2
  1.6540
2
          1.6697
2
1.6395
2
1.6447
2
1.6711
2
1.6401
2
1.6457
2
 
QCISD(TQ)         1.6737
1
  1.6788
1
          1.6949
1
1.6830
1
1.6763
1
1.7017
1
1.6846
1
1.6774
1
 
QCISD(TQ)=FULL         1.6505
2
  1.6547
2
          1.6705
2
1.6400
2
1.6453
2
1.6721
2
1.6407
2
1.6463
2
 
Coupled Cluster CCD   1.6853
2
1.6853
2
1.6758
2
1.6447
2
1.6447
2
1.6490
2
1.6518
2
1.6518
2
1.6487
2
  1.6684
2
1.6637
2
1.6531
2
  1.6687
2
1.6541
2
   
CCSD         1.6488
2
            1.6728
2
1.6673
2
1.6564
2
1.6499
2
1.6721
2
1.6573
2
1.6507
2
 
CCSD=FULL         1.6459
2
            1.6715
2
1.6653
2
1.6351
2
1.6405
2
1.6661
2
1.6358
2
1.6414
2
 
CCSD(T)         1.6524
2
            1.6771
2
1.6713
2
1.6606
2
1.6542
2
1.6767
2
1.6619
2
1.6551
2
 
CCSD(T)=FULL         1.6494
2
            1.6758
2
1.6692
2
1.6390
2
1.6444
2
1.6707
2
1.6396
2
1.6454
2
 
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 daug-cc-pVTZ

average calculated bond lengths (Å)
Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD cc-pVTZ-PP aug-cc-pVTZ-PP Def2TZVPP
hartree fock HF 1.6626
2
1.6560
2
1.6562
2
1.6466
2
1.6727
2
1.6732
2
    1.6642
1
density functional B3LYP 1.6882
2
1.6755
2
1.6812
2
1.6660
2
1.6838
2
1.6813
2
    1.6692
1
PBEPBE                 1.6770
1
Moller Plesset perturbation MP2 1.6882
2
1.6666
2
1.6724
2
1.6515
2
1.6894
2
1.6889
2
    1.6761
1
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.