****************************************************************************** 
                                                                                
                                   DESCRIPTION                                  
                                                                                
                                     OF THE                                     
                                                                                
                             OHIO STATE - LIVERMORE                             
                  SPIN-ORBIT CONFIGURATION-INTERACTION PROGRAM                  
                                     (CIDBG)                                    
                                                                                
 ****************************************************************************** 
                                                                                
                                                                                
 PROCEDURE NAME:  CIDBG                                                         
                                                                                
                                                                                
 DESCRIPTION:  This program carries out configuration-interaction calculations  
               over double-group-adapted configuration functions.  Spin-orbit   
               matrix elements are included in the Hamiltonian matrix.          
                                                                                
                                                                                
                                                                                
                                                                                
 INPUT FILE:  CIDBGIN                                                           
                                                                                
 PRINT OUTPUT FILE:  CIDBGLS                                                    
                                                                                
 LABELED INTEGRAL FILE:  MOINTS                                                 
                                                                                
 ELECTRON CONFIGURATION FILE:  (specify by unit no. in input)                   
                                                                                
 See detailed file list below for additional files                              
                                                                                
                                                                                
                                                                                
                                                                                
 DOCUMENTATION:  Russell M. Pitzer                                              
                 Department of Chemistry              Internet:                 
                 The Ohio State University            pitzer.3@osu.edu          
                 100 W. 18th Ave.                                               
                 Columbus, OH 43210                                             
                 USA                                                            
                                                                                
                                                                                
 LAST REVISION:  February, 1996                                                 
                                                                                
                                                                                
 REFERENCES:  Spin-orbit operator and matrix elements,                          
              R. M. Pitzer and N. W. Winter, J. Phys. Chem. 92, 3061 (1988)     
                                                                                
              Determinantal configuration-interaction matrix elements           
              R. C. Ladner, Ph. D. thesis, Caltech, 1972                        
              F. W. Bobrowitz, Ph. D. thesis, Caltech, 1974                     
                                                                                
              Simultaneous multiroot overrelaxation diagonalization             
              I. Shavitt, NASA-Ames Report, 1977                                
              R. C. Raffenetti, J. Comput. Phys. 32, 403, (1979)                
                                                                                

 I.  Introduction                                                               
                                                                                
      This program is designed for studying the electronic structure of         
 polyatomic molecules with very large spin-orbit interactions.  This            
 interaction and other relativistic effects are treated with core and           
 spin-orbit potentials derived from relativistic atomic calculations.  The      
 configuration-interaction expansion is in terms of double-group-adapted        
 functions and is limited in length to several thousand terms.  The program     
 works only for molecules which have C2v, D2, or D2h symmetry, or whose         
 symmetry point group includes these groups as subgroups.  Thus all diatomic    
 (and other linear) molecules can be treated using either C2v or D2h symmetry.  
                                                                                
      The integrals over molecular orbitals are obtained from the LSTRN program 
 and the list of electron configurations is obtained from the CGDBG program.    
                                                                                
                                                                                
 II.  Files                                                                     
                                                                                
      Files needed for each configuration-interaction calculation are specified 
 only by unit number.  The corresponding file names are given in job control    
 statements or generated by the operating system as the result of OPEN          
 statements.                                                                    
                                                                                
   File      Unit                                                               
   Name      No.     Description                                                
                                                                                
 (unit no.) IUNT1A   List of electron configurations from CGDBG                 
                     (defaults to 1)                                            
                                                                                
  MOINTS    IUNT1B   Integrals over MOs; from LSTRN                             
              =3                                                                
                                                                                
  CIDBGIN      5     Input                                                      
                                                                                
  CIDBGLS     IW     Output listing                                             
              =6                                                                
                                                                                
  HMATRIX   IUNT2A   Hamiltonian matrix                                         
              =8                                                                
                                                                                
 (unit no.) ICIPUN   CI vectors (optional)                                      
                                                                                
  .......   IUNTS1   Scratch file for initial configurational data              
              =11                                                               
                                                                                
                                                                                
 III.  Input Data                                                               
                                                                                
     1.  RTITLE (8A10)                                                          
                                                                                
     2.  NROOTS,ICIWRT,ICIPUN,INTWRT,IHAMRD,IANALZ,IUNT1A,MAXNE0 (16I5)         
                                                                                
     3.  ITMAX,IDGWRT,OMEGA (2I5,F10.0)                                         

     4.  For I=1,NROOTS                                                         
         NREAD,THRESH(I) (I5,F10.0)                                             
         If(NREAD.EQ.1)                                                         
            LIMIT (I5)                                                          
            For J=1,LIMIT                                                       
               IDOMNT(J),COEFF(J) (5(I5,F10.0))                                 
         If(NREAD.EQ.2)                                                         
            MDBG (I5)                                                           
            FRMT (A80)                                                          
            For J=1,MDBG                                                        
               VECTOR(J) (FRMT)                                                 
                                                                                
     5.  If(IANALZ.EQ.1)                                                        
            THRESH,IPUNCH (E10.2,I5)                                            
                                                                                
     (add similar data for another calculation or put in a blank line to        
     terminate the run)                                                         
                                                                                
     where                                                                      
                                                                                
         RTITLE              Job Title                                          
                                                                                
         NROOTS              Number of energy values to be found                
                                                                                
         ICIWRT              =  0   Minimum output                              
                             =  1   Prints all vectors                          
                             =  2   Prints the Hamiltonian matrix               
                             =  3   Prints additional wavefunction data         
                                                                                
         ICIPUN              =  0   Do not write out vectors                    
                             >  0   Write the vectors on unit ICIPUN            
                                                                                
         INTWRT              =  0   Minimum output                              
                             =  1   Prints the one-electron integrals           
                             =  2   Prints all the integrals                    
                                                                                
         IHAMRD              =  0   Compute the Hamiltonian matrix              
                             =  1   Read the Hamiltonian matrix from            
                                       unit IUNT2A                              
                                                                                
         IANALZ              =  0   No vector or energy breakdown               
                             =  1   Vector and energy breakdown                 
                                                                                
         IUNT1A              Unit for reading in number of electrons,           
                                state symmetry, configuration list, etc.        
                                (defaults to 1).  See write-up for CGDBG.       
                                                                                
         MAXNE0              (If IHAMRD = 1) Maximum number of nonzero          
                                Hamiltonian matrix elements per row, obtained   
                                from previous run's output                      
                                                                                
         ITMAX               Maximum number of diagonalization iterations       
                                (defaults to 100).                              
                                                                                
         IDGWRT              =  0   No diagonalization iteration output         
                             =  1   Diagonalization iteration results printed   
                                                                                
         OMEGA               Diagonalization over-relaxation factor; see        
                                remarks in source file (defaults to 1.4).       

         NREAD               =  0   Use unit matrix for initial vectors         
                             =  1   Read in dominant coefficients in initial    
                                       vectors                                  
                             =  2   Read in initial vectors                     
                                                                                
         THRESH(I)           Diagonalization convergence threshold (defaults to 
                                10**(-7))                                       
                                                                                
         LIMIT               (If NREAD = 1) Number of dominant coefficients in  
                                vector                                          
                                                                                
         IDOMNT(J)           (If NREAD = 1) Index of a dominant coefficient     
                                                                                
         COEFF(J)            (If NREAD = 1) Value of this dominant coefficient  
                                                                                
         MDBG                (If NREAD = 2) Number of coefficients in vector    
                                                                                
         FRMT                (If NREAD = 2) Format for reading in coefficients  
                                                                                
         VECTOR(J)           (If NREAD = 2) Coefficient values                  
                                                                                
         THRESH              (If IANALZ = 1) Threshold for the energy selection 
                                (minimum: 10**(-6), maximum: 10**(-1),          
                                defaults to 10**(-3))                           
                                                                                
         IPUNCH              (If IANALZ = 1) If non-zero, unit for writing out  
                                selected configurations (not implemented yet)   
                                                                                
                                                                                
 IV.  Notes                                                                     
                                                                                
      This program was written by R. M. Pitzer and N. W. Winter in 1984-1986,   
 in order to try out new algorithms for including the spin-orbit interaction in 
 configuration-interaction calculations.  These algorithms include (1) storing  
 only integrals over spatial functions, (2) using double-group symmetry to      
 construct matrix elements over symmetry-adapted configuration functions, and   
 (3) combining these in such a way that the Hamiltonian matrix is real even     
 though the wavefunction is not.                                                
                                                                                
      In this project, the Caltech/Los Alamos CI program was used as a starting 
 point because of its simple structure in using determinantal information to    
 form matrix elements.  This CI program originated in the W. A. Goddard group;  
 the first version was written in the spring of 1971 by R. C. Ladner and        
 P. J. Hay with some help from W. J. Hunt.  It was revised in the spring of     
 1972 by F. W. Bobrowitz.  The diagonalization method was changed to the        
 Shavitt single-root overrelaxation method in the fall of 1972 by N. W. Winter. 
 The number of configurations was increased by T. H. Dunning in the fall of     
 1973.  It was revised with the addition of selection options in the spring of  
 1975 by P. J. Hay.                                                             
                                                                                
      CIDBG is limited to expansions of several thousand configurations.  Once  
 further experience with this type of calculation is obtained, it should be     
 possible to develop a direct-CI type of program to do much larger              
 calculations.  The limitation to C2v, D2, or D2h symmetry was used in order to 
 make use of simple algorithms to keep the Hamiltonian matrix real; this        
 limitation can be reduced or eliminated with a moderate amount of effort.      

      The Department of Energy, the National Science Foundation, and Cray       
 Research, Inc., have supported this work.                                      
                                                                                
      Distribution of this program is handled primarily through Argonne         
 National Laboratory as part of the COLUMBUS system of programs.  Contact       
                            shepard@tcg.anl.gov                                 
                                                                                
                                                                                
 *******************************************************************            
                                                                                
    This computer program contains work performed partially at                  
    Lawrence Livermore National Laboratory under                                
    the auspices of the Office of Basic Energy Sciences,                        
    Division of Chemical Sciences, U.S. Department of Energy,                   
    under contract W-7405-ENG-48.                                               
                                                                                
    These programs may not be (re)distributed without the                       
    written consent of the Argonne Theoretical Chemistry Group.                 
                                                                                
    Since these programs are under development, correct results                 
    are not guaranteed.                                                         
                                                                                
 *******************************************************************            
                                                                                
                                                                                
 V.  Sample Data                                                                
                                                                                
 CH2 3B1 -- 1A1 mixing  (Total Energy: -6.50728044)                             
    2    0    0    0    0    1                                                  
    0    0                                                                      
    0                                                                           
    0                                                                           
  0.0001