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III.G.1.a.

Comparison of levels of theory for Cl-Mg


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 3.6453
2
PM3 1.9700
5
PM6 2.2118
5
composite G2 2.2378
5
G3 2.2378
5
G3B3 2.2403
5
G4 2.2234
5
CBS-Q 2.2683
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 2.2420
5
2.3015
5
2.2390
5
2.3078
5
2.2150
9
2.2378
5
2.2356
5
2.2367
5
2.2366
5
2.2176
5
2.1873
3
2.2612
5
2.2353
5
2.2157
4
2.2134
5
2.2817
2
2.2146
5
2.2356
3
2.2151
5
ROHF   2.3024
1
2.2382
1
  2.2342
1
2.2342
1
2.2373
1
2.2344
1
                     
density functional LSDA 2.1891
5
2.2467
5
2.2141
5
2.2756
5
2.2135
5
2.2135
5
2.2167
5
2.2160
5
2.2160
5
2.1932
5
    2.2132
5
2.1940
5
2.2253
2
2.2217
5
2.2291
2
2.2242
2
 
SVWN   2.2723
5
    2.1702
4
  2.2169
5
                       
BLYP 2.2360
5
2.3072
5
2.2512
5
2.3188
5
2.2570
5
2.2570
5
2.2618
5
2.2645
5
2.2647
5
2.2690
3
    2.2532
4
2.2406
4
  2.2312
3
     
B1B95 2.2210
5
2.2642
5
2.2318
5
2.2949
5
2.2301
5
2.2311
5
2.2676
3
2.2608
4
2.2608
4
2.2122
5
    2.2303
5
2.2111
5
2.2479
2
2.2368
4
2.2506
2
2.3865
1
 
B3LYP 2.2259
5
2.2948
5
2.2370
5
2.3038
5
2.2403
5
2.2403
5
2.2437
5
2.2456
5
2.3031
2
2.2212
5
2.2211
1
2.2588
5
2.2376
5
2.2227
4
2.2491
3
2.2948
2
2.2238
5
2.2482
3
2.2221
5
B3LYPultrafine         2.2403
5
                      2.1801
4
   
B3PW91 2.3693
2
2.2966
5
2.2378
5
2.3005
5
2.2354
5
2.2354
5
2.2372
5
2.2369
5
2.2888
2
2.2440
3
    2.2345
4
2.2158
4
  2.2120
3
     
mPW1PW91 2.3648
2
2.2930
5
2.2338
4
2.2966
5
2.2312
5
2.2312
5
2.2327
5
2.2318
5
2.2320
5
2.2391
3
    2.2305
4
2.2111
4
  2.2387
1
     
M06-2X         2.2255
5
                           
PBEPBE 2.3643
2
2.3016
5
2.2446
4
2.3077
4
2.2451
5
2.2451
5
2.2483
5
2.2485
5
2.2485
5
2.2252
5
2.2251
1
  2.2437
5
2.2262
5
2.2640
2
  2.1864
2
2.2627
2
 
PBEPBEultrafine         2.2148
3
                           
PBE1PBE         2.3618
5
                           
HSEh1PBE         2.2316
5
                           
TPSSh         2.3720
5
  2.3728
5
            2.3628
5
         
Moller Plesset perturbation MP2 2.4475
2
2.3116
5
2.2226
5
2.3214
5
2.2213
5
2.2213
5
2.2218
5
2.2235
5
2.2236
5
2.2171
5
  2.2579
5
2.2306
5
2.2505
2
2.2384
3
2.2816
3
2.2450
3
2.2397
3
2.2166
5
MP2=FULL 2.4450
2
2.3122
5
2.2203
4
2.3224
4
2.2188
5
2.2188
5
2.2197
5
2.2225
5
2.2661
2
2.2437
2
    2.2656
2
2.2339
2
2.2172
3
2.2249
3
  2.2239
2
2.1994
5
MP3         2.2198
5
  2.3632
5
                       
MP3=FULL         2.3618
5
  2.3634
5
                       
MP4   2.3163
4
    2.2235
5
    2.2252
1
2.2684
2
        2.2174
1
         
B2PLYP         2.2300
5
                2.3614
5
         
Configuration interaction CID   2.3670
2
2.2621
2
2.3870
2
2.2226
5
    2.2530
3
                     
CISD   2.3690
2
2.2634
2
2.3886
2
2.2235
5
    2.2694
2
                     
Quadratic configuration interaction QCISD   2.3174
5
2.2250
4
2.3298
4
2.2241
5
2.2246
4
2.2248
5
2.2249
5
2.2544
3
2.2543
2
    2.2328
5
2.2396
3
         
QCISD(T)         2.2245
5
    2.2266
1
        2.2699
2
2.2512
2
  2.2995
2
2.2576
2
   
Coupled Cluster CCD   2.3149
4
2.2229
4
2.3266
4
2.2221
5
2.2228
4
2.2221
4
2.2233
5
2.2677
2
2.2534
2
    2.2311
5
2.2511
2
  2.2963
2
2.2551
2
   
CCSD         2.2235
5
    2.2244
1
                     
CCSD(T)         2.1993
3
2.2229
1
  2.2262
1
  2.1804
2
2.2206
1
  2.2573
3
2.2397
3
  2.2855
3
2.2463
3
   
CCSD(T)=FULL         2.2590
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 2.3271
5
2.2348
5
2.3178
5
2.2330
5
2.2717
5
2.3284
5
density functional B1B95 2.2730
2
2.2166
3
       
B3LYP 2.3305
5
2.2466
5
2.3239
5
2.2458
5
2.2774
5
2.3280
5
Moller Plesset perturbation MP2 2.3430
5
2.2369
5
2.3354
5
2.2286
5
2.2796
5
2.3445
5
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.