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IV.D.1. (XII.C.1.)

Geometry Comparison

AlS (Aluminum sulfide)


distance is atom 1 (Al) to atom 2 (S)

Experimental bond length is 2.029  Å

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Calculated bond length in Å
Methods with predefined basis sets
semi-empirical PM3 1.789
PM6 1.982
composite G2 2.026
G3 2.026
G3B3 2.056
G4 2.039
CBS-Q 2.026

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 cc-pVQZ aug-cc-pVDZ aug-cc-pVTZ aug-cc-pVQZ cc-pV(T+d)Z
hartree fock HF 1.958 2.146 2.019 2.157 2.026 2.026 2.026 2.023 2.023 2.020 2.018 2.030 2.043 2.028 2.021 2.047 2.028 2.021 2.020
ROHF   2.101 2.006   2.010 2.010 2.010 2.008         2.024 2.010          
density functional LSDA 1.948 2.104 2.033 2.108 2.039 2.039 2.039 2.034 2.034 2.029     2.054 2.034   2.055      
SVWN   2.104     2.039   2.039                        
BLYP 1.974 2.141 2.066 2.148 2.076 2.076 2.076 2.072 2.072 2.065     2.089 2.071   2.092      
B1B95 1.948 2.110 2.035 2.115 2.038 2.040 dnf 2.036 2.036 2.034     2.056 2.038   dnf      
B3LYP 1.961 2.127 2.048 2.133 2.055 2.055 2.056 2.052   2.047 2.045 2.057 2.070 2.053 2.046 2.073 2.053 2.046 2.045
B3LYPultrafine         2.056                       2.043    
B3PW91   2.115 2.038 2.119 2.042 2.042 2.042 2.039   2.035     2.059 2.041   2.061      
mPW1PW91   2.112   2.115 2.038 2.038 2.038 2.034 2.035 2.031     2.054 2.037   2.057      
M06-2X         2.032                            
PBEPBE   2.127     2.059 2.059 2.059 2.056 2.056 2.051 2.049   2.074 2.056     2.056   2.049
PBEPBEultrafine         2.059                            
PBE1PBE         2.039                            
HSEh1PBE         2.041                            
TPSSh         2.039   2.039             2.038          
Moller Plesset perturbation MP2   2.090 2.021 2.091 2.025 2.025 2.026 2.023 2.023 2.026   2.032 2.047 2.032 2.024 2.056 2.034 2.024 2.027
MP2=FULL   2.091     2.024 2.024 2.024 2.024         2.046   2.002 2.055     2.023
MP3         2.031   2.030                        
MP3=FULL         2.029   2.030                        
MP4         2.045     2.042           2.051          
B2PLYP         2.045                 2.041          
Configuration interaction CID         2.031     2.027                      
CISD         2.036                            
Quadratic configuration interaction QCISD   2.160     2.050   2.050 2.045 2.046       2.077 2.054         2.047
QCISD(T)         2.053     2.048                      
Coupled Cluster CCD         2.036     2.032         2.063            
CCSD         2.044     2.040                      
CCSD(T)   2.147     2.048 2.048 2.048 2.044 2.044   2.046     2.055         2.048

Calculated bond length in Å
Methods with effective core potentials (select basis sets)
CEP-31G CEP-31G* CEP-121G CEP-121G* LANL2DZ SDD
hartree fock HF 2.158 2.034 2.160 2.032 2.151 2.149
density functional B1B95 2.140 2.065        
B3LYP 2.144 2.066 2.144 2.066 2.140 2.121
Moller Plesset perturbation MP2 2.103 2.045 2.098 2.037 2.096 2.075
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
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