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III.G.1.a.

Comparison of levels of theory for Be-Be


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 1.9567
3
PM3 1.9763
3
PM6 1.2295
4
composite G2 2.7668
4
G3 2.1505
3
G3B3 2.2178
2
CBS-Q 2.1502
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-pCVDZ cc-pCVTZ
hartree fock HF 2.3780
2		 2.1796
3		 2.1796
3		 2.1641
3		 2.1504
3		 2.1505
3		 2.1980
3		 2.1690
3		 2.2585
3		 2.1559
3		 1.7800
1		 2.1939
3		 3.7032
3		 2.2608
3		 2.2588
3		 2.4354
2		 2.2970
3		 2.4175
2		    
ROHF 2.4581
1		 2.4526
1		 2.4526
1		 2.4106
1		 2.3052
2		 2.3692
1		 2.5204
1		 2.4181
1		 2.4181
1		 2.3489
1		     2.4243
1		 2.4239
1		 2.4308
1		 4.9976
1		 4.6268
1		 4.9561
1		    
density functional LSDA 2.1265
2		 2.1988
2		 2.1988
2		 2.1995
2		 2.1927
2		 2.1927
2		 2.1953
2		 2.1815
2		 2.1815
2		 2.1909
2		     2.1993
2		 2.1852
2		 2.1754
1		 2.2011
2		 2.1859
1		 2.1810
1		    
SVWN   2.1340
3		     2.1285
3		   2.1317
3		                          
BLYP 2.3464
2		 2.1972
3		 2.1972
3		 2.1992
3		 2.1936
3		 2.1936
3		 2.1927
3		 2.1811
3		 2.1386
3		 2.2891
3		     2.1950
3		 2.2036
2		   2.0195
1		        
B1B95 2.2086
3		 2.1634
3		 2.1634
3		 2.1621
3		 2.1570
3		 2.1572
3		 2.3336
3		 2.1542
3		 2.1542
3		 2.1552
3		     2.1642
3		 2.1549
3		 2.2231
2		 2.1685
3		 2.2521
1		 2.2306
2		    
B3LYP 2.2058
3		 2.1533
3		 2.1533
3		 2.1545
3		 2.1474
3		 2.1474
3		 2.1515
3		 2.1413
3		 2.1414
3		 2.3089
3		 2.4807
1		 2.1260
3		 2.3180
3		 2.1416
3		 2.2054
2		 2.2266
2		 2.3031
3		 2.3011
3		    
B3LYPultrafine         2.1474
3		                              
B3PW91 2.3341
2		 2.1637
3		 2.1637
3		 2.1617
3		 2.1556
3		 2.1556
3		 2.1597
3		 2.1527
3		 2.1527
3		 2.3158
3		     2.1620
3		 2.1523
3		   2.0228
1		        
mPW1PW91 2.2024
3		 2.1648
3		 2.3567
3		 2.1624
3		 2.1562
3		 2.1562
3		 2.1609
3		 2.1549
3		 2.1549
3		 2.2254
2		     2.2339
2		 2.2262
2		   2.0224
1		        
M06-2X         2.1614
3		                              
PBEPBE 2.3367
2		 2.3063
3		 2.2232
2		 2.2231
2		 2.2939
3		 2.2939
3		 2.2921
3		 2.2855
3		 2.1453
3		 2.2897
3		 2.4272
1		   2.1553
3		 2.2823
3		 2.2062
2		     2.2098
2		    
PBEPBEultrafine         2.4474
1		                              
HSEh1PBE         2.1556
3		                              
Moller Plesset perturbation MP2FC 2.3635
2		 2.1121
3		 2.1121
3		 2.1088
3		 2.0754
3		 2.0754
3		 2.0901
3		 2.0918
3		 2.1683
3		 2.0928
3		   2.1547
3		 2.1793
3		 2.1621
3		 2.2213
2		 2.1894
3		 2.1669
3		 2.2298
2		 2.0367
1		 2.0170
1
MP2FU 2.3624
2		 2.1109
3		 2.2575
2		 2.2526
2		 2.0707
3		 2.0707
3		 2.0850
3		 2.0883
3		 2.1648
3		 2.2090
2		     2.1745
3		 2.1232
3		 2.1996
2		 2.2538
1		 2.0978
2		 2.2058
2		 2.0316
1		 2.0091
1
ROMP2 2.4878
1		 2.2593
1		 2.2593
1		 2.2488
1		 2.1990
1		 2.1990
1		 2.2304
1		 2.2289
1		 2.2289
1		 2.2076
1		     2.2443
1		 2.2241
1		 2.2109
1		 4.6337
1		 3.9368
1		 4.2233
1		    
MP3         2.1369
3		                              
MP4   2.2487
2		     2.0619
3		     1.8031
1		 2.2231
2		         2.2181
2		            
B2PLYP         2.1471
3		   2.1554
3		                          
Configuration interaction CID   2.2705
2		 2.2705
2		 2.2657
2		 2.0735
3		     2.0954
3		                        
CISD   2.2740
2		 2.2740
2		 2.2704
2		 2.0797
3		     2.2556
2		                        
Quadratic configuration interaction QCISD   2.1271
3		 2.2730
2		 2.2701
2		 2.0780
3		 2.2170
2		 2.1208
3		 2.1023
3		 2.2518
2		 2.2342
2		     2.2592
2		 2.2468
2		            
QCISD(T)         2.2050
2		               2.2466
2		 2.2309
2		   2.2684
2		 2.2422
2		      
Coupled Cluster CCD   2.2704
2		 2.2704
2		 2.2660
2		 2.0722
3		 2.2126
2		 2.2538
2		 2.0945
3		 2.2443
2		 2.2255
2		     2.2510
2		 2.2408
2		   2.2886
2		 2.2628
2		      
CCSD         2.0158
2		     1.8014
1		                        
CCSD(T)         2.1266
2		 1.8056
1		   1.8095
1		     2.0282
1		   2.1808
3		 2.1630
3		 2.2196
2		 2.1959
3		 2.1700
3		 2.2308
2		 2.0462
1		 2.0240
1
CCSD(T)=FULL         2.1229
2		               2.0459
1		 2.0043
1		 2.1952
2		 2.0489
1		 2.0099
1		 2.2031
2		 2.0416
1		 2.0180
1
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 2.3351
3		 2.3134
3		 2.3065
3		 2.2687
3		 2.2966
3		 2.2425
3
density functional B1B95 2.5947
1		          
B3LYP 2.2350
3		 2.2260
3		 2.2644
3		 2.1729
3		 2.1697
3		 2.1263
3
Moller Plesset perturbation MP2FC 2.2732
3		 2.2231
3		 2.2263
3		 2.1741
3		 2.2142
3		 2.1567
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.