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

Geometry Comparison

MgS (magnesium sulfide)


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

Experimental bond length is 2.143  Å

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Calculated bond length in Å
Methods with predefined basis sets
semi-empirical PM3 1.837
PM6 1.933
composite G2 2.149
G3 2.149
G3B3 2.162
G4 2.148
CBS-Q 2.149

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   2.221 2.147 2.221 2.149 2.149 2.151 2.148 2.148 2.136 2.134 2.178 2.148   2.136   2.140 2.137 2.138
density functional LSDA 1.977 2.194 2.138 2.188 2.141 2.141 2.143 2.140 2.140 2.125     2.143 2.128   2.149      
SVWN   2.194     2.141   2.143                        
BLYP   2.228 2.175 2.228 2.181 2.181 2.184 2.182 2.182 2.166           2.189      
B1B95 1.985 2.203 2.152 2.200 2.149 2.151 2.153 2.151 2.151 2.138     2.153 2.138   2.157      
B3LYP 1.999 2.214 2.157 2.213 2.162 2.162 2.165 2.163   2.148 2.149 2.175 2.162 2.151 2.149   2.153 2.149 2.150
B3LYPultrafine         2.162                       2.152    
B3PW91   2.211 2.154 2.205 2.154 2.154 2.155 2.154   2.141           2.162      
mPW1PW91 1.999 2.208   2.202 2.150 2.150 2.151 2.149 2.149 2.137           2.157      
M06-2X         2.151                            
PBEPBE   2.221     2.169 2.169 2.171 2.169 2.169 2.154 2.155   2.170 2.157         2.156
PBEPBEultrafine         2.168                            
PBE1PBE         2.150                            
HSEh1PBE         2.152                            
TPSSh         2.155   2.155             2.147          
Moller Plesset perturbation MP2   2.224 2.155 2.222 2.157 2.157 2.160 2.161 2.161 2.154   2.173 2.166   2.151 2.184 2.160 2.153 2.154
MP2=FULL   2.225     2.155 2.155 2.158 2.161             2.138 2.183     2.142
MP3         2.164   2.159                        
MP3=FULL         2.158   2.159                        
MP4         2.172     2.174           2.168          
B2PLYP         2.161                 2.152          
Configuration interaction CID         2.159     2.160                      
CISD         2.163                            
Quadratic configuration interaction QCISD   2.271     2.176   2.178 2.176 2.177       2.186 2.166         2.165
QCISD(T)         2.179     2.179                      
Coupled Cluster CCD         2.167     2.168         2.177            
CCSD         2.172     2.172                      
CCSD(T)   2.255     2.175 2.175 2.177 2.176 2.176   2.168   2.186 2.169   2.203 2.173   2.167

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 2.225 2.151 2.227 2.151 2.194 2.221
density functional B1B95   2.170        
B3LYP 2.224 2.170 2.225 2.172 2.200 2.216
Moller Plesset perturbation MP2 2.236 2.173 2.229 2.164 2.213 2.220
Values that are outliers may reflect incorrect atom numbering for different levels of theory.
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