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Release 19April 2018
NIST Standard Reference Database 101
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III.G.1.a.

Comparison of levels of theory for Be-H


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 1.4075
9
PM3 1.3600
11
PM6 1.4517
11
composite G2 1.4121
9
G3 1.4121
9
G3B3 1.4169
11
G4 1.4149
11
CBS-Q 1.4266
11

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 Def2TZVPP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pCVDZ cc-pCVTZ
hartree fock HF 1.3986
11
1.4420
11
1.4420
11
1.4386
11
1.4227
11
1.4225
11
1.4152
11
1.4287
11
1.4250
11
1.4226
11
1.3677
5
1.4193
11
1.4245
11
1.4333
11
1.4077
11
1.4206
11
1.4257
11
1.4206
11
1.4187
11
1.3417
3
1.3350
3
ROHF 1.3003
1
1.4711
7
1.4711
7
1.4650
7
1.4439
7
1.4438
7
1.4440
7
1.4585
7
1.4542
7
1.3411
1
1.3715
3
1.4489
7
1.3958
2
1.4598
7
1.4559
7
1.4526
7
1.4577
7
1.4542
7
1.4527
7
1.3508
1
1.3422
1
density functional LSDA 1.4044
9
1.4325
9
1.4325
9
1.4320
9
1.4235
9
1.4233
9
1.4150
9
1.4203
9
1.4183
9
1.4203
9
  1.4211
7
  1.4317
9
1.4154
9
  1.4208
9
1.4197
7
  1.3704
1
1.3568
1
BLYP 1.4132
11
1.4242
11
1.4242
11
1.4238
11
1.4246
11
1.4171
11
1.4105
11
1.4144
11
1.4123
11
1.4155
11
1.4376
2
1.4182
9
1.4426
2
1.4270
11
1.4072
9
  1.3932
5
1.4350
2
  1.3591
1
1.3468
1
B1B95 1.4032
11
1.4183
11
1.4183
11
1.4179
11
1.4111
11
1.4106
11
1.4034
11
1.4087
11
1.4062
11
1.4079
11
1.4076
2
1.4112
9
1.4157
2
1.4191
11
1.4042
11
1.3774
2
1.4089
11
1.4003
11
1.3654
2
1.3554
1
1.3441
1
B3LYP 1.4029
11
1.4163
11
1.4163
11
1.4158
11
1.4089
11
1.4080
11
1.4015
11
1.4064
11
1.4037
11
1.4058
11
1.3632
5
1.4039
11
1.4159
11
1.4170
11
1.4016
11
1.3984
11
1.4070
11
1.3980
11
1.3964
11
1.3396
3
1.3306
3
B3LYPultrafine   1.4027
3
    1.4090
11
1.3932
3
1.3927
3
1.3923
3
  1.4156
2
1.4110
2
1.3988
3
1.4188
2
1.4195
9
1.4072
9
  1.4138
9
1.4007
11
  1.3533
1
1.3411
1
B3PW91 1.4047
11
1.4204
11
1.4204
11
1.4201
11
1.4118
11
1.4108
11
1.4038
11
1.4107
11
1.4077
11
1.4084
11
1.3997
2
1.4128
9
1.4088
2
1.4146
9
1.4007
9
  1.3713
5
1.3996
2
  1.3590
1
1.3478
1
mPW1PW91 1.4029
11
1.4195
11
1.4195
11
1.4192
11
1.4107
11
1.4097
11
1.4028
11
1.4103
11
1.4071
11
1.4073
11
1.3981
2
1.4124
9
1.4076
2
1.4186
11
1.4050
11
  1.4150
9
1.4084
9
  1.3583
1
1.3478
1
M06-2X 1.4068
9
1.4124
9
1.4125
11
1.4142
9
1.4096
11
1.4073
9
1.4073
9
1.4107
9
1.4064
9
1.4060
9
1.4042
2
1.4059
9
1.4109
2
1.4159
9
1.4050
9
  1.4106
9
1.4033
9
  1.3544
1
1.3430
1
PBEPBE 1.4153
11
1.4306
11
1.4306
11
1.4304
11
1.4223
11
1.4214
11
1.4144
11
1.4199
11
1.4172
11
1.4190
11
1.3739
5
1.4225
9
1.4274
11
1.4308
11
1.4149
11
1.3897
2
1.4261
9
1.4179
9
1.3771
2
1.3683
1
1.3560
1
PBEPBEultrafine   1.4141
3
    1.4201
9
1.4029
3
1.4024
3
1.4018
3
  1.4221
2
1.4180
2
1.4099
3
1.4267
2
1.4321
9
1.4194
9
  1.4261
9
1.4179
9
  1.3683
1
1.3560
1
PBE1PBE 1.4104
9
1.4207
9
1.4207
9
1.4189
9
1.4132
11
1.4118
9
1.4109
9
1.4159
9
1.4127
9
1.4105
9
1.4011
2
1.4143
9
1.4107
2
1.4228
9
1.4120
9
  1.4175
9
1.4106
9
  1.3608
1
1.3492
1
HSEh1PBE 1.4106
9
1.4217
11
1.4205
9
1.4189
9
1.4132
11
1.4109
9
1.4053
11
1.4157
9
1.4125
9
1.4104
9
1.4015
2
1.4141
9
1.4111
2
1.4228
9
1.4068
11
  1.4175
9
1.4102
9
  1.3603
1
1.3486
1
TPSSh 1.4330
2
1.3787
5
1.3787
5
1.3754
5
1.3807
7
1.3672
5
1.3721
7
1.3704
5
1.4084
2
1.4159
11
1.4049
2
1.3989
3
1.4134
2
1.3772
5
1.3728
7
1.4031
2
1.3724
5
1.3646
5
1.4032
2
1.3621
1
1.3509
1
wB97X-D 1.4291
2
1.4209
2
1.4342
11
1.4184
2
1.4224
11
1.4044
2
1.4169
11
1.4093
2
1.4210
11
1.4025
2
1.4011
2
1.4205
11
1.4096
2
1.4198
11
1.4200
11
1.4000
2
1.4136
2
1.4170
11
1.4000
2
   
B97D3 1.4509
2
1.4298
11
1.4399
2
1.4380
2
1.4227
11
1.4334
2
1.4173
11
1.4379
2
1.4211
11
1.4371
2
1.4168
11
1.4457
2
1.4419
2
1.4593
2
1.4198
11
1.4320
2
1.4511
2
1.4143
11
1.4321
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 Def2TZVPP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pCVDZ cc-pCVTZ
Moller Plesset perturbation MP2 1.4076
11
1.4433
11
1.4433
11
1.4406
11
1.4191
11
1.4098
11
1.4035
11
1.4248
11
1.4155
11
1.4306
9
1.3967
2
1.4081
11
1.4144
11
1.4244
11
1.4138
11
1.4093
11
1.4193
11
1.4104
11
1.4077
11
1.3403
3
1.3327
3
MP2=FULL 1.4076
11
1.4431
11
1.4431
11
1.4405
11
1.4169
11
1.4089
11
1.4025
11
1.4248
11
1.4135
11
1.4093
11
1.3905
2
1.4161
9
1.3940
2
1.4236
11
1.4047
11
1.4034
11
1.4171
11
1.4053
9
1.4012
11
1.3392
3
1.3296
3
ROMP2 1.4565
5
1.4961
5
1.4961
5
1.4893
5
1.4607
5
1.4560
5
1.4563
5
1.4788
5
1.4715
5
1.4638
5
  1.4602
5
  1.4760
5
1.4730
5
  1.4769
5
    1.3496
1
1.3392
1
MP3         1.4180
11
  1.4089
11
      1.3982
2
1.3821
3
1.3978
2
1.3933
3
1.3778
3
        1.3513
1
1.3430
1
MP3=FULL   1.4363
2
1.4363
2
1.4345
2
1.3800
7
1.3938
2
1.3596
7
1.4221
2
1.3980
2
1.3921
2
1.3922
2
1.3811
3
1.3958
2
1.3924
3
1.3648
3
  1.4072
2
1.3730
2
  1.3502
1
1.3391
1
MP4   1.4501
9
    1.4202
9
    1.3453
3
1.4191
9
    1.4200
7
  1.4340
7
1.4202
9
  1.4352
7
1.4302
7
  1.3533
1
1.3448
1
MP4=FULL   1.4536
7
    1.4222
7
      1.4268
7
        1.4332
7
1.4231
7
  1.4329
7
1.4133
7
  1.3522
1
1.3415
1
B2PLYP 1.3937
3
1.4038
3
1.4038
3
1.4019
3
1.3783
7
1.3865
3
1.3861
3
1.3921
3
1.3850
3
1.3841
3
1.4034
2
1.3932
3
1.4094
2
1.4006
3
1.3843
5
  1.3953
3
1.3814
3
  1.3507
1
1.3396
1
B2PLYP=FULL 1.3937
3
1.4038
3
1.4038
3
1.4019
3
1.3913
3
1.3861
3
1.3857
3
1.3920
3
1.3844
3
1.3831
3
1.4017
2
1.3930
3
1.4088
2
1.4004
3
1.3789
3
  1.3942
3
1.3749
3
  1.3503
1
1.3386
1
B2PLYP=FULLultrafine 1.4329
2
1.4259
2
1.4259
2
1.4244
2
1.4130
2
1.4071
2
1.4065
2
1.4148
2
1.4064
2
1.4045
2
1.4017
2
1.4182
2
1.4088
2
1.4247
2
1.3994
2
  1.4174
2
1.3960
2
     
Configuration interaction CID   1.4499
11
1.4499
11
1.4473
11
1.4207
11
    1.4314
11
    1.4050
2
  1.4051
2
1.4212
2
1.4017
2
        1.3540
1
1.3459
1
CISD   1.4516
11
1.4516
11
1.4492
11
1.4221
11
    1.4349
11
    1.4140
2
  1.4137
2
1.4340
2
1.4108
2
        1.3560
1
1.3478
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 Def2TZVPP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pCVDZ cc-pCVTZ
Quadratic configuration interaction QCISD   1.4519
11
1.4513
11
1.4496
11
1.4222
11
1.4127
11
1.4061
11
1.4352
11
1.4207
11
1.4151
11
1.4144
2
1.4237
9
1.4140
2
1.4298
11
1.4202
11
  1.4349
9
1.3972
7
  1.3560
1
1.3478
1
QCISD(T)         1.4201
9
1.3329
3
1.3336
3
1.3482
3
      1.4212
7
  1.4286
9
1.4220
9
  1.4241
9
1.4180
9
  1.3567
1
1.3478
1
QCISD(T)=FULL         1.3572
1
  1.3437
1
            1.3579
1
1.3386
1
1.3402
1
1.3562
1
1.3211
1
1.3400
1
1.3556
1
 
QCISD(TQ)=FULL         1.3575
1
  1.3439
1
            1.3582
1
  1.3405
1
1.3565
1
1.3213
1
1.3403
1
   
Coupled Cluster CCD   1.4501
11
1.4501
11
1.4476
11
1.4206
11
1.4102
11
1.4037
11
1.4316
11
1.4175
11
1.4128
11
1.4050
2
1.4195
9
1.4051
2
1.4263
11
1.4175
11
  1.4227
11
1.4139
11
  1.3419
3
1.3366
3
CCSD         1.4146
10
1.3645
5
1.3647
5
1.3858
5
1.4187
2
1.4097
2
1.4137
2
1.4236
9
1.4134
2
1.4350
9
1.4282
9
1.3934
7
1.4346
9
1.4268
9
1.4234
9
1.3560
1
1.3478
1
CCSD=FULL         1.4229
9
        1.4064
2
1.4076
2
1.4226
9
1.4115
2
1.4339
9
1.4180
9
1.4169
9
1.4321
9
1.4079
9
1.4163
9
1.3548
1
1.3445
1
CCSD(T)         1.4200
9
1.3328
3
1.3336
3
1.3482
3
    1.3501
1
1.4212
7
  1.4285
9
1.4220
9
1.4173
9
1.4241
9
1.4180
9
1.4152
9
1.3435
3
1.3377
3
CCSD(T)=FULL         1.4192
9
            1.4202
7
  1.4339
7
1.4245
7
1.4109
9
1.4332
7
1.4143
7
1.3777
7
1.3424
3
1.3346
3
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 Def2TZVPP cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pCVDZ cc-pCVTZ

average calculated bond lengths (Å)
Methods with effective core potentials (select basis sets)
daug-cc-pVDZ daug-cc-pVTZ daug-cc-pVQZ Sadlej_pVTZ CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF         1.4570
11
1.4341
11
1.4378
11
1.4333
11
1.4437
11
1.4376
11
density functional B1B95         1.3561
3
1.3418
3
       
B3LYP         1.4328
11
1.4183
11
1.4195
11
1.4165
11
1.4197
11
1.4147
11
wB97X-D         1.4471
2
1.4262
2
1.4342
2
1.4228
2
1.4373
2
1.4372
2
Moller Plesset perturbation MP2         1.4614
11
1.4347
11
1.4408
11
1.4296
11
1.4460
11
1.4387
11
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.