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III.G.1.a.

Comparison of levels of theory for S-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 2.8392
1
PM3 2.1095
2
PM6 2.0153
3
composite G2 2.2058
3
G3 2.2058
3
G3B3 2.2236
3
G4 2.2078
3
CBS-Q 2.2058
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 2.1073
2
2.3044
3
2.2042
3
2.3377
3
2.2058
6
2.2058
3
2.2083
3
2.2062
3
2.2063
3
2.1925
3
2.1344
1
2.2571
3
2.2039
3
2.2221
2
2.1927
3
2.2433
2
2.1970
3
2.1939
3
2.1376
1
ROHF         2.2516
1
                           
density functional LSDA 2.0531
3
2.2183
3
2.1998
3
2.2579
3
2.2016
3
2.2016
3
2.2035
3
2.2011
3
2.2011
3
2.1859
3
    2.2030
3
2.1876
3
2.2004
1
2.2108
3
2.2188
2
2.2010
1
 
SVWN   2.2612
3
    2.1788
2
  2.2036
3
                       
BLYP 2.1280
2
2.2984
3
2.2387
3
2.3018
3
2.2446
3
2.2446
3
2.2475
3
2.2464
3
2.2465
3
2.2294
3
    2.2754
2
2.2635
2
  2.1891
1
     
B1B95 2.0628
3
2.2268
3
2.2098
3
2.2706
3
2.2104
3
2.2111
3
2.2125
3
2.2113
3
2.2113
3
2.1978
3
    2.2121
3
2.1976
3
2.2260
2
2.2191
3
2.2294
2
2.2259
2
 
B3LYP 2.0758
3
2.2820
3
2.2193
3
2.2839
3
2.2236
3
2.2236
3
2.2260
3
2.2249
3
2.2558
2
2.2091
3
2.1492
1
2.2492
3
2.2231
3
2.2114
3
2.2095
3
2.2631
2
2.2135
3
2.2099
3
2.1502
1
B3LYPultrafine         2.2238
3
                      2.2107
3
   
B3PW91 2.1056
2
2.2786
3
2.2153
3
2.2754
3
2.2143
3
2.2143
3
2.2158
3
2.2144
3
2.2447
2
2.2006
3
    2.2454
2
2.2316
2
  2.1615
1
     
mPW1PW91 2.0677
3
2.2751
3
2.2417
2
2.2716
3
2.2098
3
2.2098
3
2.2113
3
2.2100
3
2.2099
3
2.1964
3
    2.2405
2
2.2272
2
  2.1574
1
     
M06-2X         2.2037
3
                           
PBEPBE 2.1137
2
2.2905
3
2.2613
2
2.3251
2
2.2307
3
2.2307
3
2.2326
3
2.2315
3
2.2315
3
2.2163
3
2.1547
1
  2.2318
3
2.2179
3
2.2466
2
    2.2470
2
2.1560
1
PBEPBEultrafine         2.1683
1
                           
PBE1PBE         2.2105
3
                           
HSEh1PBE         2.2123
3
                           
TPSSh         2.1941
3
  2.1948
3
            2.1861
3
         
Moller Plesset perturbation MP2 2.0905
2
2.2746
3
2.2082
3
2.2709
3
2.2090
3
2.2090
3
2.2124
3
2.2123
3
2.2123
3
2.2059
3
  2.2310
3
2.2188
3
2.2341
2
2.2047
3
2.2394
3
2.2140
3
2.2004
2
2.1544
1
MP2=FULL 2.0908
2
2.2756
3
2.2318
2
2.2959
2
2.2069
3
2.2069
3
2.2101
3
2.2122
3
2.2378
2
2.2224
2
    2.2444
2
2.2195
2
2.1899
3
2.1832
1
  2.2173
2
2.1415
1
MP3         2.2100
3
  2.1909
3
                       
MP3=FULL         2.1893
3
  2.1909
3
                       
MP4   2.3127
2
    2.2217
3
    2.1741
1
2.2481
2
        2.2169
3
         
B2PLYP         2.2175
3
                2.1882
3
         
Configuration interaction CID   2.3118
2
2.2314
2
2.3100
2
2.2087
3
    2.2104
3
                     
CISD   2.3343
2
2.2361
2
2.3395
2
2.2131
3
    2.2396
2
                     
Quadratic configuration interaction QCISD   2.3289
3
2.2454
2
2.3635
2
2.2242
3
2.2480
2
2.2263
3
2.2248
3
2.2249
3
2.2367
2
    2.2331
3
2.2138
3
        2.1649
1
QCISD(T)         2.2285
3
    2.1793
1
        2.2641
2
2.2439
2
  2.2832
2
2.2501
2
   
Coupled Cluster CCD   2.3134
2
2.2339
2
2.3117
2
2.2132
3
2.2362
2
2.2397
2
2.2149
3
2.2383
2
2.2303
2
    2.2229
3
2.2318
2
  2.2671
2
2.2371
2
   
CCSD         2.2193
3
    2.1720
1
                     
CCSD(T)   2.2548
1
    2.1747
1
2.1747
1
2.1768
1
2.1757
1
2.1757
1
  2.1675
1
  2.2357
3
2.2177
3
  2.2547
3
2.2234
3
  2.1674
1
CCSD(T)=FULL         2.2471
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 2.3778
2
2.2101
3
2.3786
3
2.2088
3
2.2630
3
2.3415
3
density functional B1B95   2.1698
1
       
B3LYP 2.2976
3
2.2319
3
2.2974
3
2.2322
3
2.2722
3
2.2864
3
Moller Plesset perturbation MP2 2.2872
3
2.2287
3
2.2740
3
2.2162
3
2.2722
3
2.2698
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.