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III.G.1.a.

Comparison of levels of theory for Cl-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 1.4365
4
PM3 1.3252
6
PM6 1.7086
6
composite G2 1.7806
5
G3 1.6949
6
G3B3 1.4697
6
G4 1.3035
5
CBS-Q 1.7806
5

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) 6-311+G(3df,2pd) 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 cc-pCVDZ cc-pCVTZ Sadlej_pVTZ
hartree fock HF 1.5386
6
1.6647
6
1.6466
6
1.7228
6
1.5062
11
1.6735
6
1.9156
6
1.7739
6
1.6845
6
1.6744
6
1.2640
2
1.2644
1
1.6298
6
1.5729
6
1.5828
6
1.2841
5
1.2977
6
1.2858
6
1.2842
5
1.2725
2
1.5800
6
1.2940
3
1.2834
3
1.2819
1
ROHF         1.2936
1
                                     
density functional LSDA 1.5184
6
1.4709
6
1.4609
6
1.4924
6
1.4560
6
1.4515
6
1.4404
6
1.4493
6
1.4387
6
1.4489
6
1.2883
1
1.2887
1
1.2966
1
1.4499
6
1.4328
6
1.3202
4
1.3436
6
1.3260
6
1.3203
4
1.2989
2
1.2890
1
1.3024
1
1.2897
1
 
SVWN 1.3449
1
1.4934
6
1.2970
1
1.3299
1
1.3114
4
1.2941
1
1.4404
6
1.3011
1
1.2948
1
1.2911
1
1.2883
1
1.2887
1
1.2966
1
1.3033
1
1.2918
1
1.2903
1
1.3032
1
1.2921
1
1.2904
1
1.2988
1
1.2890
1
1.3024
1
1.2897
1
 
BLYP 1.5393
6
1.5221
6
1.4925
6
1.5254
6
1.4897
6
1.4831
6
1.4776
6
1.4790
6
1.4695
6
1.4825
6
1.2894
1
1.2897
1
1.2984
1
1.4840
6
1.4650
6
1.2912
1
1.3053
2
1.2930
1
1.2913
1
1.3023
2
1.2900
1
1.3061
1
1.2907
1
 
B1B95 1.5191
6
1.4794
6
1.4704
6
1.4999
6
1.4653
6
1.4602
6
1.4631
6
1.4623
6
1.4532
6
1.4600
6
1.2742
1
1.2745
1
1.2824
1
1.4589
6
1.4454
6
1.3032
4
1.3194
6
1.3083
5
1.3033
4
1.2845
2
1.2749
1
1.2882
1
1.2754
1
 
B3LYP 1.5212
6
1.5017
6
1.4728
6
1.5037
6
1.4697
6
1.4644
6
1.4646
6
1.4650
6
1.5405
4
1.4637
6
1.2801
2
1.2800
1
1.4550
6
1.4639
6
1.4493
6
1.3031
5
1.3312
6
1.3120
6
1.3032
5
1.2918
2
1.4459
6
1.3157
3
1.3022
3
1.2983
1
B3LYPultrafine 1.3419
1
1.3164
1
1.2889
1
1.3204
1
1.4691
6
1.2863
1
1.2871
1
1.2923
1
1.2871
1
1.2838
1
1.2800
1
1.2800
1
1.2892
1
1.2966
1
1.2835
1
1.2819
1
1.2950
1
1.3035
5
1.2820
1
1.2921
1
1.2808
1
1.2956
1
1.2814
1
 
B3PW91 1.6101
4
1.4941
6
1.4653
6
1.4945
6
1.4604
6
1.4551
6
1.4560
6
1.4574
6
1.5281
4
1.4540
6
1.2780
1
1.2784
1
1.2866
1
1.4529
6
1.4394
6
1.2800
1
1.2922
2
1.2817
1
1.2800
1
1.2882
2
1.2788
1
1.2920
1
1.2795
1
 
mPW1PW91 1.6059
4
1.4911
6
1.4984
5
1.4916
6
1.4577
6
1.4525
6
1.4554
6
1.4562
6
1.4452
6
1.4511
6
1.2757
1
1.2761
1
1.2843
1
1.4493
6
1.4369
6
1.2779
1
1.2899
2
1.2800
1
1.2780
1
1.2858
2
1.2767
1
1.2895
1
1.2773
1
 
M06-2X 1.3304
1
1.3083
1
1.2833
1
1.3131
1
1.4679
6
1.2800
1
1.2800
1
1.2863
1
1.2817
1
1.2784
1
1.2762
1
1.2764
1
1.2838
1
1.2906
1
1.2788
1
1.2773
1
1.2894
1
1.2790
1
1.2773
1
1.2862
2
1.2764
1
1.2899
1
1.2768
1
 
PBEPBE 1.5692
5
1.5068
6
1.5128
5
1.5439
5
1.4725
6
1.4663
6
1.4629
6
1.4656
6
1.4542
6
1.4652
6
1.2874
2
1.2878
1
1.2958
1
1.4638
6
1.4476
6
1.3172
4
1.3016
1
1.2912
2
1.3173
4
1.2981
2
1.2883
2
1.3020
1
1.2890
1
1.3055
1
PBEPBEultrafine 1.3491
1
1.3245
1
1.2962
1
1.3279
1
1.2967
2
1.2928
1
1.2936
1
1.2995
1
1.2939
1
1.2905
1
1.2875
1
1.2880
1
1.2959
1
1.3025
1
1.2911
1
1.2896
1
1.3020
1
1.2913
1
1.2898
1
1.2982
1
1.2884
1
1.3015
1
1.2891
1
 
PBE1PBE 1.3360
1
1.3112
1
1.2840
1
1.3135
1
1.7034
6
1.2806
1
1.2813
1
1.2878
1
1.2829
1
1.2790
1
1.2769
1
1.2773
1
1.2853
1
1.2910
1
1.2800
1
1.2789
1
1.2906
1
1.2807
1
1.2791
1
1.2867
1
1.2778
1
1.2902
1
1.2784
1
 
HSEh1PBE 1.3363
1
1.3116
1
1.2843
1
1.3145
1
1.4596
6
1.2809
1
1.2817
1
1.2881
1
1.2831
1
1.2793
1
1.2769
1
1.2774
1
1.2854
1
1.2913
1
1.2805
1
1.2790
1
1.2908
1
1.2808
1
1.2792
1
1.2868
2
1.2778
1
1.2905
1
1.2784
1
 
TPSSh         1.7236
6
  1.7267
6
              1.5878
6
                 
Moller Plesset perturbation MP2 1.3902
3
1.6331
6
1.5964
6
1.6752
6
1.5636
7
1.5338
6
1.8997
6
1.6284
6
1.5226
6
1.5486
6
1.2719
1
1.2714
1
1.4673
6
1.4689
6
1.4268
7
1.2927
5
1.3129
6
1.2966
6
1.2984
4
1.2802
2
1.4495
6
1.2987
4
1.2862
4
1.2976
1
MP2=FULL 1.3746
4
1.6313
6
1.6564
5
1.7424
5
1.5585
7
1.5293
6
1.8844
6
1.6247
6
1.6438
4
1.5959
5
1.2713
1
1.2693
1
1.2763
1
1.4670
6
1.4835
5
1.2913
5
1.2867
2
1.2710
1
1.2967
4
1.2784
2
1.4450
6
1.2978
4
1.2847
4
 
MP3 1.3357
1
1.3177
1
1.2815
1
1.3214
1
1.6063
6
1.2702
1
1.7290
6
1.2865
1
1.2739
1
1.2753
1
1.2729
1
1.2717
1
1.2770
1
1.2868
1
1.2738
1
1.2735
1
1.2891
1
1.2752
1
1.2741
1
1.2819
1
1.2713
1
1.2859
1
1.2713
1
 
MP3=FULL         1.7363
6
  1.7341
6
                                 
MP4 1.3397
1
1.6279
6
1.2841
1
1.3245
1
1.5876
6
1.2722
1
1.2730
1
1.2903
2
1.5028
5
1.2774
1
1.2762
1
1.2748
1
1.2794
1
1.2887
1
1.5035
4
1.2763
1
1.2914
1
1.2783
1
1.2773
1
1.2836
2
1.2742
1
1.2878
1
1.2742
1
 
MP4=FULL 1.3397
1
1.3211
1
1.2841
1
1.3245
1
1.2854
1
1.2711
1
1.2719
1
1.2903
1
1.2766
1
1.2754
1
1.2753
1
1.2729
1
1.2800
1
1.2874
1
1.2746
1
1.2750
1
1.2900
1
1.2745
1
1.2757
1
1.2818
1
1.2719
1
1.2869
1
1.2730
1
 
B2PLYP         1.4744
6
                  1.8085
5
                 
Configuration interaction CID 1.3414
1
1.6987
5
1.6657
5
1.7500
5
1.6193
6
1.2699
1
1.2705
1
1.6182
6
1.2736
1
1.2737
1
1.2710
1
1.2699
1
1.2764
1
1.2859
1
1.2722
2
1.2712
1
1.2871
1
1.2726
1
1.2716
1
1.2809
1
1.2696
1
1.2850
1
1.2697
1
 
CISD 1.3425
1
1.6199
6
1.6550
5
1.7080
5
1.5968
6
  1.2712
1
1.6577
5
1.2738
1
1.2738
1
1.2711
1
1.2704
1
1.2771
1
1.2865
1
1.2727
2
1.2716
1
1.2878
1
1.2731
1
1.2721
1
1.2815
1
1.2701
1
1.2856
1
1.2702
1
 
Quadratic configuration interaction QCISD 1.3425
1
1.6129
6
1.5486
7
1.6884
5
1.5698
6
1.5030
6
1.8860
6
1.5618
6
1.4970
5
1.5688
5
1.2745
1
1.2732
1
1.2793
1
1.4573
6
1.4411
6
1.2746
1
1.2907
1
1.2766
1
1.2752
1
1.2838
2
1.2875
4
1.3058
3
1.2923
3
 
QCISD(T) 1.3426
1
1.3234
1
1.2857
1
1.3265
1
1.5636
6
1.2734
2
1.2743
2
1.2919
2
1.2776
1
1.2783
1
1.2769
1
1.2755
1
1.2807
1
1.4559
6
1.4391
6
1.2768
1
1.3222
5
1.3054
5
1.2777
1
  1.2749
1
1.2891
1
1.2749
1
 
QCISD(TQ)   1.3236
1
1.2859
1
1.3267
1
1.2872
1
1.2736
1
1.2745
1
1.2917
1
1.2777
1
1.2785
1
1.2770
1
1.2756
1
1.2809
1
1.2902
1
1.2774
1
1.2769
1
1.2926
1
1.2791
1
1.2779
1
1.2851
1
1.2750
1
1.2893
1
1.2751
1
 
Coupled Cluster CCD 1.3414
1
1.6338
6
1.6575
5
1.7455
5
1.6050
6
1.5207
6
1.8969
6
1.5995
6
1.5079
5
1.5895
5
1.2737
1
1.2724
1
1.2784
1
1.4565
6
1.4407
6
1.2740
1
1.3182
5
1.3011
5
1.2745
1
1.2830
2
1.2917
3
1.3050
3
1.2917
3
 
CCSD 1.3425
1
1.3228
1
1.2843
1
1.3261
1
1.7022
4
1.2724
2
1.2731
2
1.2898
2
1.2759
1
1.2769
1
1.2744
1
1.2731
1
1.2793
1
1.2892
2
1.2755
2
1.2745
1
1.2906
1
1.2765
1
1.2751
1
1.2839
1
1.2727
1
1.2879
1
1.2728
1
 
CCSD=FULL 1.3424
1
1.3229
1
1.2842
1
1.3260
1
1.2856
1
1.2713
1
1.2719
1
1.2897
1
1.2761
1
1.2748
1
1.2733
1
1.2710
1
1.2794
1
1.2874
1
1.2731
1
1.2728
1
1.2892
1
1.2725
1
1.2733
1
1.2819
1
1.2702
1
1.2867
1
1.2710
1
 
CCSD(T) 1.3426
1
1.3235
1
1.2857
1
1.3265
1
1.6133
5
1.2734
2
1.2743
2
1.2919
2
1.2776
1
1.2783
1
1.2768
2
1.2754
1
1.2806
1
1.4558
6
1.4390
6
1.2969
2
1.3221
5
1.3053
5
1.2976
2
1.2848
1
1.4360
6
1.3025
4
1.2894
4
 
CCSD(T)=FULL 1.3426
1
1.3235
1
1.2857
1
1.3265
1
1.3044
4
1.2723
1
1.2731
1
1.2919
1
1.2778
1
1.2763
1
1.2759
1
1.2735
1
1.2808
1
1.3063
3
1.2950
3
1.2953
2
1.3098
3
1.2948
3
1.2959
2
1.2830
2
1.2921
3
1.3013
4
1.2880
4
 

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 1.7710
6
1.7481
6
1.7045
6
1.6746
6
1.6350
6
1.6395
6
density functional LSDA 1.3431
1
1.3121
1
1.3484
1
1.3130
1
1.3310
1
1.3283
1
SVWN 1.3431
1
1.3121
1
1.3484
1
1.3130
1
1.3310
1
1.3283
1
BLYP 1.3407
1
1.3103
1
1.3450
1
1.3090
1
1.3270
1
1.3308
1
B1B95 1.3246
2
1.2969
2
1.3294
2
1.2959
2
1.3115
2
1.3110
2
B3LYP 1.5252
6
1.4926
6
1.4998
6
1.4610
6
1.4981
6
1.4996
6
B3LYPultrafine 1.3279
1
1.2990
1
1.3328
1
1.2989
1
1.3149
1
1.3182
1
B3PW91 1.3238
1
1.2961
1
1.3304
1
1.2965
1
1.3124
1
1.3151
1
mPW1PW91 1.3210
1
1.2933
1
1.3270
1
1.2937
1
1.3092
1
1.3120
1
M06-2X 1.3210
1
1.2939
1
1.3256
1
1.2936
1
1.3083
1
1.3115
1
PBEPBE 1.3367
1
1.3069
1
1.3419
1
1.3068
1
1.3236
1
1.3263
1
PBEPBEultrafine 1.3367
1
1.3069
1
1.3419
1
1.3068
1
1.3236
1
1.3261
1
PBE1PBE 1.3221
1
1.2943
1
1.3280
1
1.2946
1
1.3100
1
1.3127
1
HSEh1PBE 1.3225
1
1.2946
1
1.3282
1
1.2949
1
1.3104
1
1.3132
1
Moller Plesset perturbation MP2 1.7515
6
1.7167
6
1.6377
6
1.5638
6
1.5998
6
1.6054
6
MP2=FULL 1.3209
1
1.2895
1
1.3279
1
1.2894
1
1.3067
1
1.3153
1
MP3 1.3265
1
1.2935
1
1.3328
1
1.2929
1
1.3116
1
1.3184
1
MP4 1.3295
1
1.2959
1
1.3364
1
1.2956
1
1.3146
1
1.3218
1
MP4=FULL 1.3295
1
1.2959
1
1.3364
1
1.2956
1
1.3146
1
1.3228
1
Configuration interaction CID 1.3288
1
1.2927
1
1.3350
1
1.2920
1
1.3141
1
1.3201
1
CISD 1.3300
1
1.2930
1
1.3363
1
1.2923
1
1.3154
1
1.3216
1
Quadratic configuration interaction QCISD 1.3314
1
1.2958
1
1.3382
1
1.2959
1
1.3165
1
1.3236
1
QCISD(T) 1.3316
1
1.2974
1
1.3388
1
1.2972
1
1.3169
1
1.3243
1
QCISD(TQ) 1.3317
1
1.2977
1
1.3389
1
1.2976
1
1.3170
1
1.3245
1
Coupled Cluster CCD 1.3300
1
1.2954
1
1.3367
1
1.2950
1
1.3151
1
1.3219
1
CCSD 1.3313
1
1.2958
1
1.3381
1
1.2960
1
1.3164
1
1.3236
1
CCSD=FULL 1.3313
1
1.2958
1
1.3381
1
1.2960
1
1.3164
1
1.3243
1
CCSD(T) 1.3316
1
1.2974
1
1.3387
1
1.2972
1
1.3169
1
1.3243
1
CCSD(T)=FULL 1.3316
1
1.2974
1
1.3387
1
1.2972
1
1.3169
1
1.3252
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.