return to home page Computational Chemistry Comparison and Benchmark DataBase Release 22 (May 2022) Standard Reference Database 101 National Institute of Standards and Technology
You are here: Home > Geometry > Comparisons > Bonds, angles OR Comparisons > Geometry > Bonds, angles

Geometry Comparison

As2 (Arsenic diatomic)


distance is atom 1 (As) to atom 2 (As)

Experimental bond length is 2.103  Å

Display Options
Switch to bar chart display
Calculated bond length in Å
Methods with predefined basis sets
semi-empirical PM6 1.934
composite G2 2.026
G3 2.050
G3B3 2.124
G4 2.115
CBS-Q 2.027

Calculated bond length in 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 aug-cc-pVDZ aug-cc-pVTZ daug-cc-pVTZ
hartree fock HF 1.979 2.121 2.065 2.086 2.049 2.049 2.055 2.064 2.064 2.032   2.063 2.061 2.061 2.065 2.061 2.061
density functional LSDA 1.980 2.097 2.097 2.116 2.084 2.084 2.090 2.097 2.097 2.058     2.099 2.090 2.100 2.090  
BLYP 2.004 2.192 2.138 2.161 2.131 2.127 2.133 2.142 2.142 2.098     2.142 2.135      
B1B95 1.992   2.089 2.110 2.074 2.074 2.080 2.090 2.090 2.052     2.088 2.084 2.090 2.084  
B3LYP 1.997 2.163 2.110 2.132 2.097 2.097 2.103 2.112 2.112 2.072   2.110 2.112 2.105 2.113 2.105  
B3LYPultrafine         2.097                     2.114  
B3PW91 1.997 2.157 2.102 2.122 2.086 2.086 2.092 2.101 2.101 2.063     2.100 2.095      
mPW1PW91 1.994 2.152 2.097 2.116 2.080 2.080 2.086 2.095 2.095 2.058     2.094 2.089 2.096 2.089  
M06-2X     2.101               2.086            
PBEPBE 1.999 2.183 2.126 2.145 2.110 2.110 2.116 2.126 2.126 2.083     2.125 2.119 2.126 2.119  
PBE1PBE         2.080                        
TPSSh         2.086   2.092     2.052       2.096      
wB97X-D     2.078   2.058   2.066   2.078     2.077 2.066 2.072   2.071  
B97D3   2.183     2.111   2.118   2.130   2.119 2.123   2.120   2.117 2.117
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 aug-cc-pVDZ aug-cc-pVTZ daug-cc-pVTZ
Moller Plesset perturbation MP2 2.106 2.281 2.159 2.223 2.153 2.152 2.157 2.167 2.166 2.108   2.144 2.156 2.127 2.159 2.128  
MP2=FULL 2.105 2.281 2.156 2.220 2.142 2.142 2.147 2.154 2.154 2.078     2.153 2.120 2.157 2.115  
MP3         2.106   2.108                    
MP3=FULL         2.100   2.106                    
MP4   2.248     2.148       2.164         2.133      
B2PLYP                           2.122      
B2PLYP=FULLultrafine         2.116               2.130 2.117   2.115  
Configuration interaction CID   2.180 2.102 2.140 2.094     2.105                  
CISD   2.183 2.104 2.142 2.096     2.107                  
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 aug-cc-pVDZ aug-cc-pVTZ daug-cc-pVTZ
Quadratic configuration interaction QCISD   2.217 2.128 2.169 2.119 2.119 2.125 2.131 2.131 2.082     2.124 2.099 2.127 2.098  
QCISD(T)         2.137               2.141 2.117      
Coupled Cluster CCD   2.210 2.122 2.164 2.114 2.114 2.119 2.124 2.124 2.077     2.118 2.093 2.121 2.092  
CCSD         2.117               2.122 2.097      
CCSD(T)         2.136               2.140 2.116 2.144 2.116  
CCSD(T)=FULL         2.129               2.138 2.111 2.142 2.105  
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 aug-cc-pVDZ aug-cc-pVTZ daug-cc-pVTZ

Calculated bond length in 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 2.116   2.116   2.138 2.114     2.041
density functional B3LYP 2.169   2.169   2.193 2.164     2.105
PBEPBE                 2.122
Moller Plesset perturbation MP2 2.283   2.283   2.303 2.268     2.130
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
Please use the error report form to report problems.