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LB1

Member

Registered: 2023-10-20

Posts: 2

[SOLVED] MCPDFT can't interpret results from GAS / GASSCF?

Dear developers,

The MCPDFT module crashes with an error (Too many active electrons) because it can't interpret the active spaces of GAS, and thinks there's no active space at all:

 ###    ERROR: Too many active electrons.                                    ###
  Too many active electrons NACTEL=    10
 Cannot be more than 2*Nr of active orbitals=     0

One solution floating around the office is if that if you're using GAS, MCPDFT requires you to copy the GASSCF block into the MCPDFT section (despite this not being listed in the manual), however this error persists regardless of if you do this.

Input file:

(GATEWAY, SEWARD (Cholesky), SCF)

&RASSCF
  Symmetry = 1
  Spin     = 1
  nActEl   = 10 0 0
*      D2h : Ag B3u B2u B1g B1u B2g B3g  Au
  Inactive = 14   4  11   2  12   4   9   2
  GASSCF
    4
       5   0   0   0   4   0   0   0
    4 4
       0   2   0   0   0   2   0   0
    6 6
       0   0   2   0   0   0   2   0
    8 8
       0   0   0   2   0   0   0   2
    10 10
  3RDM

&MCPDFT
  KSDFT = FT:PBE
  CIONLY
  symmetry=1
  spin=1
  nActEl = 10 0 0
  Inactive = 14   4  11   2  12   4   9   2
  GASSCF	
    4
       5   0   0   0   4   0   0   0
    4 4
       0   2   0   0   0   2   0   0
    6 6
       0   0   2   0   0   0   2   0
    8 8
       0   0   0   2   0   0   0   2
    10 10

End of input

Is this a known issue with a workaround? I haven't been able to find anything on it on the forums so far.

Last edited by LB1 (2024-01-03 18:27:21)

LB1

Member

Registered: 2023-10-20

Posts: 2

Re: [SOLVED] MCPDFT can't interpret results from GAS / GASSCF?

Update: I've discovered a workaround: include what the RAS2 block would be if not partitioned, i.e. the sum of all the GASes. When given GAS and RAS, the &RASSCF module will ignore RAS and compute GAS, but it will still pass on the RAS2 line to &MCPDFT and be interpreted correctly.

(GATEWAY, SEWARD (Cholesky), SCF)

&RASSCF
  Symmetry = 1
  Spin     = 1
  nActEl   = 10 0 0
*      D2h : Ag B3u B2u B1g B1u B2g B3g  Au
  Inactive = 14   4  11   2  12   4   9   2
  GASSCF
    4
              5   0   0   0   4   0   0   0
       4  4
              0   2   0   0   0   2   0   0
       6  6
              0   0   2   0   0   0   2   0
       8  8
              0   0   0   2   0   0   0   2
      10 10
  RAS2     =  5   2   2   2   4   2   2   2
  3RDM

&MCPDFT
  KSDFT = FT:PBE

End of input