Subject: failure of stability calculation to converge

From: "Mills, Nancy S." <[email-masked]>
Date: Tue, 25 Feb 2003 15:00:39 -0600

I am checking the stability of the wavefunctions for a set of hydrocarbon dications. For 5 of the 7 compounds, the calculation with the keyword "stable" completed and indicated that the wavefunction was stable. However, for two of the calculations, the convergence of the roots was going along well and then the convergence began to fall apart. I have included the data for a couple of interations that seem to be progressing properly and the final two interations where the convergence fails. Does anyone have any suggestions for the source of the problem and how I can correct it? Thanks much. If there is interest, I will summarize the responses.

Iteration    21 Dimension   115                                         
CISAX:  IP=  1 NPass=   1 NMax=   2.                                    
CISAX will form   2 AO SS matrices at one time.                         
NMat=  2 NSing=  2.                                                     
Root      1 has converged.                                              
Root      2 has converged.                                              
Root      3 has converged.                                              
Root      4 has converged.                                              
Root      5 not converged, maximum delta is    0.000112452573916        
Root      6 not converged, maximum delta is    0.000213035457487        
Excitation Energies [eV] at current iteration:                          
Root      1 :     0.426822039406661   Change is   -0.000000000000006    
Root      2 :     0.530296318031781   Change is   -0.000000000000005    
Root      3 :     0.905696326131997   Change is   -0.000000000000015    
Root      4 :     1.099568214079369   Change is   -0.000000000317104    
Root      5 :     1.154377740579626   Change is    0.000000000000001    
Root      6 :     1.306447028821338   Change is   -0.000002447923274    

Iteration    22 Dimension   117                                       
CISAX:  IP=  1 NPass=   1 NMax=   2.                                  
CISAX will form   2 AO SS matrices at one time.                       
NMat=  2 NSing=  2.                                                   
Root      1 has converged.                                            
Root      2 has converged.                                            
Root      3 has converged.                                            
Root      4 not converged, maximum delta is    0.000100026640287      
Root      5 not converged, maximum delta is    0.000384607267230      
Root      6 not converged, maximum delta is    0.000413563563639      
Excitation Energies [eV] at current iteration:                        
Root      1 :     0.426822039406656   Change is   -0.000000000000005  
Root      2 :     0.530296318031785   Change is    0.000000000000004  
Root      3 :     0.905696326132015   Change is    0.000000000000019  
Root      4 :     1.099568196675160   Change is   -0.000000017404208  
Root      5 :     1.154377740579620   Change is   -0.000000000000006  
Root      6 :     1.306430104314072   Change is   -0.000016924507266  

Iteration    29 Dimension   141                                               
CISAX:  IP=  1 NPass=   1 NMax=   6.                                          
CISAX will form   6 AO SS matrices at one time.                               
NMat=  6 NSing=  3.                                                           
No map to state      1                                                        
Root      2 not converged, maximum delta is    0.625775957881971              
Root      3 not converged, maximum delta is    0.616299008719543              
Root      4 not converged, maximum delta is    0.614387011977500              
Root      5 not converged, maximum delta is    0.540143333190759              
Root      6 not converged, maximum delta is    0.583506855980462              
Excitation Energies [eV] at current iteration:                                
Root      1 :     0.001850847422398                                           
Root      2 :     0.426822032992069   Change is   -0.000000006414581          
Root      3 :     0.530296313038704   Change is   -0.000000004993080          
Root      4 :     0.905696322297265   Change is   -0.000000003834752          
Root      5 :     1.145469971130768   Change is   -0.000722189979634          
Root      6 :     1.154325191308280   Change is   -0.000052549271337          
Iteration    30 Dimension   147                                               
CISAX:  IP=  1 NPass=   1 NMax=   6. 

Iteration    30 Dimension   147                                               
CISAX:  IP=  1 NPass=   1 NMax=   6.                                          
CISAX will form   6 AO SS matrices at one time.                               
NMat=  6 NSing=  3.                                                           
No map to state      1                                                        
Root      2 not converged, maximum delta is    0.626079759542003              
Root      3 not converged, maximum delta is    0.616298833910727              
Root      4 not converged, maximum delta is    0.614386954343650              
Root      5 not converged, maximum delta is    0.556683156184800              
Root      6 not converged, maximum delta is    0.572819977565145              
Excitation Energies [eV] at current iteration:                                
Root      1 :     0.000224020053891                                           
Root      2 :     0.426822028271046   Change is   -0.000000004721023          
Root      3 :     0.530296309492499   Change is   -0.000000003546205          
Root      4 :     0.905696319574155   Change is   -0.000000002723110          
Root      5 :     1.145435582981513   Change is   -0.000034388149256          
Root      6 :     1.154312440040871   Change is   -0.000012751267409          
Iteration    31 Dimension   153                                               
CISAX:  IP=  1 NPass=   1 NMax=   6.                                          
CISAX will form   6 AO SS matrices at one time.                               
NMat=  6 NSing=  3.                                                           
Orthogonalize current: ORTVEC returned   152 roots                            
Error termination via Lnk1e in /usr/local/src/gaussian/g98/l914.exe.                                                                                  
Job cpu time:  1 days  2 hours 46 minutes 45.4 seconds.                      
File lengths (MBytes):  RWF=  653 Int=    0 D2E=    0 Chk=   28 Scr=    1    

Nancy S. Mills, Ph. D.                          Phone, (210) 999-7317
Professor                                             Fax, (210) 999-7569
Department of Chemistry                       [email-masked]
Trinity University
715 Stadium Dr.
San Antonio, TX  78212-7200