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Release 17bSeptember 2015
NIST Standard Reference Database 101
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III.G.1.a.

Comparison of levels of theory for Al-Cl


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 2.0814
11
PM3 2.2240
10
PM6 2.1138
17
composite G2 2.1464
17
G3 2.1464
17
G3B3 2.1549
17
G4 2.1482
17
CBS-Q 2.1459
17

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 aug-cc-pV(T+d)Z
hartree fock HF 2.1282
17
2.2375
17
2.1416
17
2.2466
17
2.1462
17
2.1458
17
2.1593
14
2.1386
17
2.1386
17
2.1400
17
2.0650
6
2.1492
17
2.1690
17
2.1447
17
2.1492
1
2.1692
17
2.1422
17
2.1494
1
2.1339
15
2.1772
9
ROHF         2.1880
2
                             
density functional LSDA 2.1213
17
2.1492
17
2.1215
17
2.2209
17
2.1293
17
2.1293
17
2.1280
17
2.1231
17
2.1231
17
2.1154
15
  2.1655
9
2.1515
17
2.1266
17
  2.1499
17
2.1572
11
  2.1530
9
2.1528
9
SVWN   2.2090
17
2.1388
1
2.2588
1
2.1293
17
2.1627
9
2.1280
17
2.1565
9
2.1565
9
2.1540
9
  2.1001
9
2.1857
9
2.1611
9
2.1353
1
2.1852
9
2.1608
9
2.1353
1
2.1530
9
2.1528
9
BLYP 2.1591
17
2.2528
17
2.1637
17
2.2702
17
2.2099
17
2.1744
17
2.1737
17
2.1706
17
2.1706
17
2.1650
17
  2.2149
9
2.1959
17
2.1727
17
  2.1225
6
    2.2026
9
2.2026
9
B1B95 2.1317
17
2.1602
17
2.1324
17
2.2321
17
2.1378
17
2.1384
17
2.1435
16
2.1326
17
2.1326
17
2.1325
17
  2.1756
9
2.1611
17
2.1375
17
  2.1655
16
2.1834
10
  2.1666
9
2.1664
9
B3LYP 2.1436
17
2.2368
17
2.1466
17
2.2509
17
2.1552
17
2.1552
17
2.1541
17
2.1504
17
2.1891
11
2.1469
17
2.0735
6
2.1585
17
2.1771
17
2.1538
17
2.1620
1
2.1762
17
2.1509
17
2.1623
1
2.1405
15
2.1836
9
B3LYPultrafine         2.1553
17
            2.1950
9
2.2145
9
2.1479
15
  2.2149
9
2.1513
17
  2.1836
9
2.1836
9
B3PW91 2.1761
11
2.2313
17
2.1408
17
2.2419
17
2.1463
17
2.1463
17
2.1448
17
2.1400
17
2.1770
11
2.1394
17
  2.1852
9
2.1690
17
2.1451
17
  2.1002
6
    2.1751
9
2.1751
9
mPW1PW91 2.1717
11
2.2271
17
2.1714
11
2.2370
17
2.1417
17
2.1417
17
2.1401
17
2.1353
17
2.1354
17
2.1349
17
  2.1804
9
2.1645
17
2.1406
17
  2.1594
15
2.1774
9
  2.1705
9
2.1706
9
M06-2X 2.1489
9
2.2501
9
2.1874
17
2.2674
9
2.1377
17
2.1726
9
2.1723
9
2.1658
9
2.1658
9
2.1668
9
  2.1744
9
2.1962
9
2.1710
9
  2.1961
9
2.1710
9
  2.1650
9
2.1651
9
PBEPBE 2.1844
11
2.2404
17
2.1866
11
2.2974
11
2.1589
17
2.1589
17
2.1578
17
2.1537
17
2.1536
17
2.1506
17
2.0785
6
2.1978
9
2.1810
17
2.1575
17
  2.2182
9
2.1520
15
  2.1868
9
2.1865
9
PBEPBEultrafine         2.1531
15
            2.1979
9
2.2178
9
2.1945
9
  2.2183
9
2.1945
9
  2.1868
9
2.1865
9
PBE1PBE 2.1539
9
2.1694
9
2.1694
9
2.2740
9
2.1412
17
2.1765
9
2.1763
9
2.1703
9
2.1703
9
2.1707
9
  2.1796
9
2.2000
9
2.1767
9
  2.2004
9
2.1766
9
  2.1698
9
2.1697
9
HSEh1PBE 2.1550
9
2.2283
17
2.1711
9
2.2763
9
2.1428
17
2.1783
9
2.1413
17
2.1722
9
2.1722
9
2.1722
9
  2.1815
9
2.2018
9
2.1416
17
  2.2023
9
2.1782
9
  2.1713
9
2.1712
9
TPSSh   2.2696
9
2.1780
9
2.2823
9
2.1942
17
2.1842
9
2.1938
17
2.1776
9
  2.1920
17
  2.1875
9
2.2078
9
2.1941
17
  2.2084
9
2.1845
9
  2.1776
9
2.1778
9
wB97X-D     2.1910
17
  2.1925
17
      2.1892
17
        2.1924
17
    2.1918
17
     
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 aug-cc-pV(T+d)Z
Moller Plesset perturbation MP2 2.1746
11
2.2532
17
2.1276
17
2.2673
17
2.1861
17
2.1326
17
2.1318
17
2.1820
17
2.1258
17
2.1350
17
  2.1398
17
2.1663
17
2.1419
17
2.1440
1
2.1762
17
2.1750
11
2.1459
1
2.1358
17
2.1723
9
MP2=FULL 2.1739
11
2.2530
17
2.1574
11
2.3127
11
2.1289
17
2.1289
17
2.1273
17
2.1236
17
2.1575
11
2.1559
11
  2.1721
9
2.1632
17
2.1674
11
2.1102
1
2.1664
15
2.1679
9
2.1012
1
2.1231
17
2.1560
9
MP3         2.1335
17
  2.1835
17
        2.1764
9
2.2048
9
2.1796
9
        2.1738
9
2.1748
9
MP3=FULL         2.1813
17
  2.1809
17
        2.1747
9
2.2014
9
2.1711
9
        2.1618
9
2.1607
9
MP4   2.3027
11
    2.1375
17
      2.1647
11
    2.1795
9
2.2081
9
2.1672
10
  2.2184
9
2.1615
1
  2.1757
9
2.1772
9
MP4=FULL   2.2953
9
    2.1693
9
2.1382
1
2.1412
1
2.1375
1
2.1625
9
2.1353
1
  2.1509
1
2.2045
9
2.1728
9
  2.2123
9
2.1496
1
  2.1630
9
2.1409
1
B2PLYP 2.1578
9
2.2755
9
2.1711
9
2.2922
9
2.1440
17
2.1797
9
2.1796
9
2.1736
9
2.1736
9
2.1765
9
  2.1843
9
2.2069
9
2.1780
17
  2.2110
9
2.1836
9
  2.1763
9
2.1768
9
B2PLYP=FULL 2.1576
9
2.2753
9
2.1700
9
2.2921
9
2.1784
9
2.1784
9
2.1785
9
2.1728
9
2.1728
9
2.1723
9
  2.1835
9
2.2057
9
2.1802
9
  2.2091
9
2.1801
9
  2.1721
9
2.1720
9
B2PLYP=FULLultrafine         2.0779
6
                             
Configuration interaction CID   2.2934
11
2.1646
11
2.3111
11
2.1346
17
    2.1624
11
                    2.1683
9
2.1683
9
CISD   2.2947
11
2.1653
11
2.3125
11
2.1351
17
    2.1631
11
                    2.1685
9
2.1684
9
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 aug-cc-pV(T+d)Z
Quadratic configuration interaction QCISD   2.2598
17
2.1657
11
2.3236
11
2.1371
17
2.1721
11
2.1700
11
2.1292
17
2.1292
17
2.1733
11
  2.1789
9
2.2090
11
2.1803
11
  2.2164
9
2.1813
9
  2.1746
9
2.1752
9
QCISD(T)         2.1733
11
            2.1803
9
2.2105
11
2.1819
11
  2.2202
11
2.1666
3
  2.1762
9
2.1775
9
Coupled Cluster CCD   2.2999
11
2.1635
11
2.3194
11
2.1350
17
2.1700
11
2.1678
11
2.1619
11
2.1619
11
2.1720
11
  2.1771
9
2.2068
11
2.1790
11
  2.2156
11
2.1771
11
  2.1734
9
2.1741
9
CCSD         2.1364
17
            2.1784
9
2.2067
9
2.1800
9
2.1429
1
2.2157
9
2.1808
9
2.1448
1
2.1742
9
2.1507
1
CCSD=FULL         2.1683
9
            2.1766
9
2.2032
9
2.1713
9
2.1099
1
2.2099
9
2.1461
1
2.1011
1
2.1618
9
2.1370
1
CCSD(T)         2.1380
17
            2.1800
9
2.2099
11
2.1815
11
2.1447
1
2.2197
11
2.1805
11
2.1471
1
2.1760
9
2.1533
1
CCSD(T)=FULL         2.1693
11
            2.1781
9
2.2049
9
2.1730
9
2.1110
1
2.2123
9
2.1488
1
2.1024
1
2.1394
1
2.1399
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 cc-pVDZ cc-pVTZ cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z aug-cc-pV(T+d)Z

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 2.2451
17
2.1509
17
2.2473
17
2.1512
17
2.2392
17
2.2289
17
density functional B1B95 2.1683
6
2.0926
6
       
B3LYP 2.2607
17
2.1668
17
2.2601
17
2.1666
17
2.2536
17
2.2396
17
Moller Plesset perturbation MP2 2.2686
17
2.1473
17
2.2694
17
2.1445
17
2.2539
17
2.2446
17
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.