No CI determinants for given double group irrep

[Giorgio Visentin]

Dear sirs,

I am performing a KRCI computation for N2. I would like to get the energy for the ground state. This is ^1\Sigma_g, so it should correspond to 2\Omega_p = 0g.

I thus set up the following input, where I also specified some low-lying metastable states:

**DIRAC
.WAVE FUNCTION
.ANALYZE
**INTEGRALS
*READIN
.UNCONTRACT
**HAMILTONIAN
.X2C
**GENERAL
*PARALLEL
.NTASK
8
**MOLECULE
*BASIS
.DEFAULT
s-aug-dyall.cv4z
**WAVE FUNCTIONS
.SCF
.KRCI
*SCF
.MAXITR
2000
*KRCI
.CI PROGRAM
LUCIAREL
.GAS SHELLS
4
3 4 / 1 1
6 8 / 1 1
11 14 / 3 3
14 14 / 72 72
.CIROOTS
 0g 2
.CIROOTS
 2g 3
.CIROOTS
 4g 1
.CIROOTS
 0u 2
.CIROOTS
 2u 2
.MAX CI
 600
.MXCIVE
 30
.NOOCCN
.ANALYZ
.TRDM
.DIPMOM
**ANALYZE

.MULPOP
*MULPOP
.VECPOP
1..oo
1..oo
*END OF INPUT

There, I set (1s +1s') as the GAS 1, which should account for a single excitation. GAS 2 consists of GAS 1 + (2s + 2s') and should account for a double excitation, while GAS 3 consists of the previous GASs plus (2p + 2p') and accounts for a triple excitation. GAS 4 considers the virtual orbitals. The apex " ' " stands for the orbital of the second N atom.

Upon reaching the first KRCI computation, I get the following output:
&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
&&& KRCI calculation for symmetry no.    1
&&& Number of CI roots for this symmetry       2
&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&

  //  LUCIAREL called
  //  CIRUN = NDET
  //  The number of CI determinants will be computed

 *** warning: resetting LCSBLK from   100000000 to:   563549986


  Number of determinants per double group irrep
  =============================================
           213503014            64855712            64855712          -353126411          -353126411
          -964953679          -964953679         -1669320565         -1669320565          1929157055
          1929157055          1317863626          1317863626           834541259           834541259
           487972893           487972893           262109013           262109013           128463250
           128463250            56937890            56937890            22548152            22548152
             7846012             7846012             2343285             2343285              593876
              593876              223476           213503008            64857010            64857010
          -353126413          -353126413          -964952579          -964952579         -1669320566
         -1669320566          1929157839          1929157839          1317863631          1317863631
           834541726           834541726           487972894           487972894           262109240
           262109240           128463250           128463250            56937976            56937976
            22548152            22548152             7846033             7846033             2343285
             2343285              593878              593878              223476                   0
                   0                   0                   0                   0                   0
                   0                   0                   0                   0                   0
                   0                   0                   0                   0                   0
                   0                   0                   0                   0                   0
                   0                   0                   0                   0                   0
                   0                   0                   0                   0                   0
                   0                   0                   0                   0                   0
                   0                   0                   0                   0                   0
                   0                   0                   0                   0                   0
                   0                   0                   0                   0                   0
                   0                   0                   0                   0                   0
                   0                   0                   0                   0                   0
                   0                   0                   0

 (RSETCI) Number of determinants:  -2147483648 (dimension  -2147483648)

 CPU (Wall) time for generation of determinants:  5.91587700s( 6.72400000s)

 INFO: no determinants in this symmetry!

INFO: CI skipped because no determinants in this symmetry

and then the computation crashes with the following explanation:

  Determination of operator representation in KRCI module
  _______________________________________________________

  operator     boson rep in DIRAC     boson rep in KR-CI
  ________     __________________     __________________
   X dipole            B3u                  B3u
   Y dipole            B2u                  B2u
   Z dipole            B1u                  B1u

 *** warning: resetting LCSBLK from   100000000 to:   563549986


 *** warning: resetting LCSBLK from   100000000 to:   563549986

  *** ERROR in Z_BLKFO_XPROP: max number of TTSS blocks is zero.

  Master node : --- SEVERE ERROR, PROGRAM WILL BE ABORTED ---

 Date and time (Linux) : Fri Jun  2 14:02:47 2023
 *** Z_BLKFO_XPROP: max number of TTSS blocks is                   zero ***

Since the 0g should correspond to ^1/Sigma_g states, I wonder why the program cannot find the energy for this root. Is the issue related to the memory allocation, the input itself or something else?

I thank you very much for your patience and time.

Yours, faithfully,

Giorgio Visentin

[Ayaki Sunaga]

Dear Giorgio,

I tried a calculation with the following small active space and small basis sets. However, your error does not appear, and CI step starts, as attached.

(I stopped the calculation just after the CI step starts)

*BASIS                                                                                              
.DEFAULT                                                                                            
dyall.2zp  

.GAS SHELLS                                                                                        
4                                                                                                  
3 4 / 1 1                                                                                          
6 8 / 1 1                                                                                          
11 14 / 3 3                                                                                        

14 14 / 10 10  

I recommend that you should start a calculation with smaller active space and smaller basis sets.

Best regards,
Ayaki

2023年6月2日(金) 21:54 Giorgio Visentin <grgvi...@gmail.com>:

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[Hans Jørgen Aagaard Jensen]

Dear Giorgio,

 

The negative number of determinants is probably because the number of determinants becomes bigger than what can be described with a 32-bit integer.

 

Best regards Hans Jørgen.

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