CDFT-CI crashes for charged separated states

Questions
#1

I have a question with regard to CDFT-CI

For the ethane molecule the program (ver. 5.4.2) crashes,
when I want to include CH3+ and CH3- states. input see below.

Best regards

Peter

Starting CDFT-CI SCF calculation on state 1 …

Q-Chem fatal error occurred in module qparser/read_cdft.C, line 406:
Invalid data format for CDFTCI!

$molecule
    0 1
H        1.021000000      0.000000000      1.164000000
C        0.000000000      0.000000000      0.765000000
H       -0.511000000     -0.884000000      1.164000000
H       -0.511000000      0.884000000      1.164000000
C        0.000000000      0.000000000     -0.765000000
H        0.511000000     -0.884000000     -1.164000000
H        0.511000000      0.884000000     -1.164000000
H       -1.021000000      0.000000000     -1.164000000
$end

$rem
   METHOD           = b3lyp
   BASIS            = cc-pvdz
   SYMMETRY         = off
   SYM_IGNORE       = true
   UNRESTRICTED     = true
   SCF_CONVERGENCE  = 7
   MAX_SCF_CYCLES   = 600
CDFT_MAXITER 1222
SYM_IGNORE   true
   SYMMETRY     false
CDFTCI           = true
   CDFTCI_PRINT     = 2
   CDFT_THRESH      = 7
$end

$cdft
   2.0
  -1.0   1   4
   0.0
   0.0  1   4 s
---
   2.0
   1.0   1   4
   0.0
   0.0   1   4 s
---
   2.0
  -1.0   1   4 S
--------------
   2.0
  1.0   1   4 S
$end
#2

Can you please repost your input file using the “preformatted text” option ( </> button). Some of the linebreak characters disappeared in your copy/paste and I want to make sure that I have your intended input file. Q-Chem is rejecting this based on the format of the $cdft section but it’s not immediately clear to me what is wrong.

#3

hi, Peter,
Can you explain more on the constraints in the $cdft section? Your molecule is neutral in total (net charge = 0), and the block

2.0
-1.0 1 4
0.0
0.0 1 4 s

means the charge constrained in the fragment consisting of atom 1-4 is 2. Are you trying to calculate a state like CH3(2-)CH3(2+)? The 0 coefficient in the line 0.0 1 4 s enforces no constraint more than “no. of alpha electrons = no. of beta electrons” in this fragment. For the blocks

2.0
-1.0 1 4 S

and

2.0
1.0 1 4 S

, are you trying to calculate the quadriradicals CH3(down,down)CH3(up,up) and CH3(up,up)CH3(down,down)?