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Comparison of levels of theory for Si-Br


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 2.2134
8
PM3 1.8276
8
PM6 2.1965
8
composite G2 2.1952
8
G3 2.2153
8
G3B3 2.2351
8
G4 2.2265
8
CBS-Q 2.1888
8

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-pVDZ daug-cc-pVTZ
hartree fock HF 2.2022
8
2.3196
8
2.1749
8
2.2837
8
2.1953
8
2.1955
8
2.2029
8
2.2105
8
2.2108
8
2.1863
8
2.2035
3
2.2191
8
2.2236
8
2.2108
8
2.2049
3
2.2297
8
2.2114
8
2.2050
3
2.2090
2
2.2048
7
ROHF   2.3147
2
2.1495
2
2.2883
2
2.1704
2
2.1704
2
2.1752
2
2.1815
2
2.1815
2
  2.1765
2
2.1910
2
2.1987
2
2.1826
2
2.1779
2
2.2065
2
2.1832
2
2.1780
2
2.1289
1
2.1084
1
density functional LSDA 2.2089
6
2.1846
1
2.1555
6
2.2602
6
2.1841
6
2.1843
6
2.1935
6
2.2014
6
2.2016
6
2.1685
6
2.2156
1
2.2061
6
2.2148
6
2.1972
6
  2.2162
6
2.1971
6
     
BLYP 2.2401
8
2.3531
8
2.1991
8
2.3170
8
2.2313
8
2.2315
8
2.2412
8
2.2515
8
2.2518
8
2.2158
8
2.2379
3
2.2565
8
2.2627
8
2.2467
8
  2.2661
8
2.2472
8
  2.2464
2
2.2252
2
B1B95 2.2055
8
2.1612
3
2.1606
8
2.2698
8
2.1835
8
2.1835
8
2.1914
8
2.2001
8
2.2004
8
2.1730
8
2.2334
2
2.2060
8
2.2126
8
2.1986
8
  2.2161
8
2.1990
8
  2.2673
1
2.1784
2
B3LYP 2.2226
8
2.3283
8
2.1809
8
2.2947
8
2.2091
8
2.2093
8
2.2179
8
2.2269
8
2.2271
8
2.1952
8
2.2147
3
2.2326
8
2.2390
8
2.2235
8
2.2158
3
2.2426
8
2.2239
8
2.2158
3
2.2228
2
2.2018
2
B3LYPultrafine   2.3283
8
    2.2093
8
2.2095
8
2.2181
8
2.2270
8
  2.1958
3
2.2147
3
2.2328
8
2.2391
8
2.2237
8
  2.2427
8
2.2241
8
  2.2228
2
2.2018
2
B3PW91 2.2147
8
2.3156
8
2.1715
8
2.2815
8
2.1957
8
2.1958
8
2.2035
8
2.2122
8
2.2125
8
2.1833
8
2.2006
3
2.2180
8
2.2248
8
2.2098
8
  2.2283
8
2.2103
8
  2.2091
2
2.1888
2
mPW1PW91 2.2100
8
2.3098
8
2.1675
8
2.2763
8
2.1905
8
2.1908
8
2.1984
8
2.2068
8
2.2071
8
2.1787
8
2.1954
3
2.2128
8
2.2193
8
2.2048
8
  2.2230
8
2.2053
8
  2.2040
2
2.1837
2
M06-2X 2.2021
8
2.3064
8
2.1695
8
2.2719
8
2.1892
8
2.1894
8
2.1969
8
2.2061
8
2.2064
8
2.1797
8
2.1999
8
2.2139
8
2.2176
8
2.2059
8
  2.2219
8
2.2062
8
  2.2061
2
2.1875
2
PBEPBE 2.2238
8
2.3301
8
2.1825
8
2.2947
8
2.2090
8
2.2091
8
2.2176
8
2.2277
8
2.2279
8
2.1957
8
2.2155
3
2.2328
8
2.2391
8
2.2242
8
  2.2424
8
2.2247
8
  2.2246
2
2.2044
2
PBEPBEultrafine   2.3301
8
    2.2092
8
2.2094
8
2.2179
8
2.2279
8
  2.1969
3
2.2155
3
2.2330
8
2.2392
8
2.2244
8
  2.2425
8
2.2250
8
  2.2246
2
2.2044
2
PBE1PBE 2.2078
8
2.1668
3
2.1668
8
2.2753
8
2.1895
8
2.1895
8
2.1972
8
2.2060
8
2.2064
8
2.1779
8
2.1949
3
2.2120
8
2.2183
8
2.2041
8
  2.2220
8
2.2047
8
  2.2034
2
2.1833
2
HSEh1PBE 2.2091
8
2.3120
8
2.1691
8
2.2785
8
2.1921
8
2.1923
8
2.2000
8
2.2090
8
2.2093
8
2.1802
8
2.1979
3
2.2151
8
2.2214
8
2.2070
8
  2.2250
8
2.2075
8
  2.2065
2
2.1864
2
TPSSh 2.2175
8
2.3235
8
2.1748
8
2.2853
8
2.1971
8
2.1972
8
2.2050
8
2.2143
8
2.2146
8
2.1846
8
2.2033
3
2.2204
8
2.2272
8
2.2117
8
2.2050
3
2.2307
8
2.2121
8
2.2050
3
2.2121
2
2.1910
2
wB97X-D 2.2087
8
2.3016
8
2.1652
8
2.2692
8
2.1861
8
2.1862
8
2.1937
8
2.2017
8
2.2019
8
2.1750
8
2.1871
3
2.2081
8
2.2139
8
2.2004
8
2.1888
3
2.2180
8
2.2010
8
2.1888
3
2.1956
2
2.1754
2
B97D3 2.2360
8
2.3389
8
2.1886
8
2.3017
8
2.2162
8
2.2164
8
2.2251
8
2.2359
8
2.2361
8
2.2019
8
2.2290
8
2.2412
8
2.2472
8
2.2313
8
2.2259
3
2.2508
8
2.2315
8
2.2258
3
2.2340
2
2.2318
8
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-pVDZ daug-cc-pVTZ
Moller Plesset perturbation MP2 2.2145
8
2.3399
8
2.1712
8
2.3057
8
2.1997
8
2.1994
8
2.2070
8
2.2041
8
2.2037
8
2.1798
8
2.1949
3
2.2122
8
2.2218
8
2.1975
8
2.1851
3
2.2397
4
2.2039
4
2.1852
3
2.2131
2
2.1791
2
MP2=FULL 2.2140
8
2.3404
8
2.1681
8
2.3049
8
2.1944
8
2.1939
8
2.2019
8
2.2003
8
2.2001
8
2.1619
8
2.1867
3
2.2119
8
2.2188
8
2.1886
8
2.1802
3
2.2367
4
2.1923
4
2.1781
3
2.2104
2
2.1670
2
ROMP2 2.2349
1
2.2040
1
2.2040
1
2.3725
1
2.2379
1
2.2379
1
2.2450
1
2.2414
1
2.2414
1
2.2138
1
2.2315
1
2.2504
1
2.2600
1
2.2321
1
  2.2745
1
       
MP3         2.1967
7
  2.2043
7
      2.1710
2
2.2100
7
2.2191
7
2.1964
7
        2.1383
1
2.1087
1
MP3=FULL   2.3329
7
2.1658
7
2.2971
7
2.1917
7
2.1914
7
2.1994
7
2.1988
7
2.1985
7
2.1624
7
2.1654
2
2.2103
7
2.2165
7
2.1887
7
  2.2238
3
2.1818
3
  2.1361
1
2.1001
1
MP4   2.3543
2
    2.1833
2
      2.1843
2
  2.1796
2
2.1953
2
2.2074
2
2.1810
2
  2.2199
2
2.1833
2
  2.1539
1
2.1226
1
MP4=FULL   2.3612
3
    2.1948
3
      2.1987
3
  2.1735
2
  2.2189
3
2.1890
3
  2.2317
3
2.1881
3
  2.1515
1
2.1133
1
B2PLYP 2.2175
8
2.3309
8
2.1756
8
2.2968
8
2.2031
8
2.2031
8
2.2113
8
2.2160
8
2.2161
8
2.1878
8
2.2063
3
2.2231
8
2.2302
8
2.2124
8
  2.2364
8
2.2129
8
  2.2185
2
2.1930
2
B2PLYP=FULL 2.2173
8
2.3310
8
2.1745
8
2.2965
8
2.2014
8
2.2014
8
2.2097
8
2.2150
8
2.2150
8
2.1821
8
2.1784
2
2.2230
8
2.2292
8
2.2096
8
  2.2354
8
2.2090
8
  2.2176
2
2.1893
2
B2PLYP=FULLultrafine 2.2175
8
2.3310
8
2.1747
8
2.2965
8
2.2015
8
2.2015
8
2.2098
8
2.2151
8
2.2152
8
2.1822
8
2.2038
3
2.2231
8
2.2293
8
2.2098
8
  2.2355
8
2.2092
8
  2.2177
2
2.1893
2
Configuration interaction CID   2.3383
8
2.1717
8
2.3040
8
2.1985
8
    2.2051
8
    2.1950
3
  2.2222
3
2.1965
3
        2.2108
2
2.1774
2
CISD   2.3417
8
2.1725
8
2.3066
8
2.1992
8
    2.2061
8
    2.1963
3
  2.2242
3
2.1975
3
        2.2130
2
2.1786
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-pVDZ daug-cc-pVTZ
Quadratic configuration interaction QCISD   2.3542
8
2.1775
8
2.3167
8
2.2063
8
2.2060
8
2.2137
8
2.2120
8
2.2116
8
2.1876
8
2.2020
3
2.2207
8
2.2299
8
2.2055
8
  2.2393
8
2.2047
8
  2.2221
2
2.1858
2
QCISD(T)         2.2204
7
    2.2286
7
    2.2483
2
2.2371
7
2.2450
7
2.2209
7
  2.2833
3
2.2450
3
  2.2971
1
2.2576
1
QCISD(T)=FULL         2.2146
7
  2.2230
7
      2.2417
2
  2.2418
7
2.2337
3
2.2381
1
2.2801
3
2.2331
3
  2.2942
1
2.2435
1
QCISD(TQ)         2.2468
1
          2.2412
1
      2.2304
1
2.2861
1
2.2450
1
     
Coupled Cluster CCD   2.3452
8
2.1749
8
2.3102
8
2.2036
8
2.2033
8
2.2111
8
2.2089
8
2.2085
8
2.1850
8
2.1977
3
2.2175
8
2.2265
8
2.2030
8
  2.2358
8
2.2022
8
  2.2150
2
2.1808
2
CCSD         2.2050
8
2.2038
3
2.2096
3
2.2066
3
2.2063
3
2.1863
8
2.1997
3
2.2195
8
2.2283
8
2.2045
8
2.1895
3
2.2455
4
2.2090
4
2.1898
3
2.2182
2
2.1833
2
CCSD=FULL         2.1997
8
        2.1766
4
2.1930
3
2.2193
8
2.2254
8
2.1961
8
2.1854
3
2.2427
4
2.1981
4
2.1834
3
2.2156
2
2.1719
2
CCSD(T)         2.2199
7
2.2194
7
2.2280
7
2.2280
7
2.2273
7
2.2009
7
2.2471
2
2.2366
7
2.2444
7
2.2204
7
2.2368
2
2.2823
3
2.2442
3
2.2369
2
2.2958
1
2.2567
1
CCSD(T)=FULL         2.2017
8
          2.1971
3
2.2228
8
2.2284
8
2.2029
4
2.1892
3
2.2465
4
2.2021
4
2.1873
3
2.2207
2
2.1767
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-pVDZ 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 2.3220
8
  2.3213
8
  2.3214
8
2.3125
8
2.2592
1
  2.2083
8
ROHF                 2.1770
2
density functional LSDA             2.2380
1
  2.2148
1
BLYP             2.2967
1
  2.2368
3
B1B95             2.2449
1
  2.1904
3
B3LYP 2.3479
8
  2.3468
8
  2.3441
8
2.3324
8
2.2719
1
  2.2204
8
B3LYPultrafine             2.2719
1
  2.2140
3
B3PW91             2.2561
1
  2.2004
3
mPW1PW91             2.2499
1
  2.1956
3
M06-2X             2.2573
1
  2.2021
3
PBEPBE             2.2701
1
  2.2214
8
PBEPBEultrafine             2.2701
1
  2.2152
3
PBE1PBE             2.2486
1
  2.1950
3
HSEh1PBE             2.2527
1
  2.1980
3
TPSSh             2.2583
1
  2.2034
3
wB97X-D 2.3202
8
  2.3189
8
  2.3151
8
2.2988
8
2.2423
1
  2.1876
3
B97D3             2.2843
1
  2.2241
3
Moller Plesset perturbation MP2 2.3540
8
  2.3512
8
  2.3419
8
2.3364
8
2.2390
1
  2.1886
8
MP2=FULL             2.2320
1
  2.1849
3
ROMP2                 2.2239
1
MP3             2.2457
1
  2.1650
2
MP3=FULL             2.2375
1
  2.1636
2
MP4             2.2491
1
  2.1733
2
MP4=FULL             2.2420
1
  2.1713
2
B2PLYP             2.2583
1
  2.2038
3
B2PLYP=FULL             2.2559
1
  2.2028
3
B2PLYP=FULLultrafine             2.2559
1
  2.2028
3
Configuration interaction CID             2.2438
1
  2.1885
3
CISD             2.2445
1
  2.1894
3
Quadratic configuration interaction QCISD             2.2496
1
  2.1962
3
QCISD(T)             2.2509
1
  2.2421
2
QCISD(T)=FULL             2.2438
1
  2.2392
2
Coupled Cluster CCD             2.2468
1
  2.1920
3
CCSD             2.2484
1
  2.1941
3
CCSD=FULL             2.2407
1
  2.1913
3
CCSD(T)             2.2501
1
  2.2412
2
CCSD(T)=FULL             2.2430
1
  2.1951
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.