IRC in Z-matrix coordinates

I am attempting to carry out an IRC calculation in Z-matrix coordinates, as specified in section 9.7.1 of the 6.2 manual. This is accomplished with RPATH_COORDS = 2 in the $rem section. However, the calculation dies with the following error:

 Calculating analytic gradient of the SCF energy
 Gradient of SCF Energy
            1           2           3           4           5           6
    1  -0.0000000  -0.0000000   0.0000000  -0.0000000   0.0000000  -0.0000000
    2   0.0000000   0.0000000  -0.0000090   0.0000090  -0.0000000   0.0000080
    3   0.0000014  -0.0000030  -0.0000033  -0.0000033   0.0000040   0.0000021
            7
    1   0.0000000
    2  -0.0000080
    3   0.0000021
 Max gradient component =       8.956E-06
 RMS gradient           =       4.064E-06
 Gradient time:  CPU 66.10 s  wall 3.20 s
 ------------------------------------------------------------------------
 Reaction path following.  The coordinates are z-matrix
 Step   1 E=   -1603.289061 |G|=  0.000019 S_lin= 0.0000 S_tot= 0.0000
 ------------------------------------------------------------------------
 IRC -- neg. force constant =  -4.316797616690993E-003
 IRC -- max trans/rot const =   3.328729052861884E-004
 First IRC step, with rxn. path sign =            1

 Q-Chem fatal error occurred in module 0, line  122:

 First_IRC_step: Illegal value of coordinates

Below you’ll find the full input and output (with authors and multipoles trimmed to fit the character limit).

Input:

$comment
  Frequency calculation on TS. (Optimized in another job...)
$end

$molecule
  0   1
  Fe
  C   1   rFeC_Head
  X1  1   rFeC_Legs  2  a_90
  C   1   rFeC_Legs  2  a_CH_CL     3 d_90
  C   1   rFeC_Legs  2  a_nCH_CL    3 d_90
  X2  1   rFeO_Legs  2  a_90        3 d_0
  O   1   rFeO_Head  2  a_0         3 d_0
  O   1   rFeO_Legs  7  a_OL_Fe_OH  6 d_90
  O   1   rFeO_Legs  7  a_nOL_Fe_OH 6 d_90

  rFeC_Head   =    1.85674
  rFeC_Legs   =    1.85118
  rFeO_Head   =    2.99827
  rFeO_Legs   =    2.98752
  a_nCH_CL    = -108.48350
  a_CH_CL     =  108.48350
  a_nOL_Fe_OH = -105.21160
  a_OL_Fe_OH  =  105.21160
  a_0         =    0.00000
  a_90        =   90.00000
  d_0         =    0.00000
  d_90        =   90.00000
$end

$rem
  JOBTYPE              FREQ
  METHOD               wB97M-V   
  UNRESTRICTED         FALSE
  BASIS                PCSEG-1
  SYMMETRY             FALSE
  SYM_IGNORE           TRUE
  GEN_SCFMAN           TRUE
  SCF_ALGORITHM        DIIS_GDM
  SCF_CONVERGENCE      8
  MAX_SCF_CYCLES       200
  THRESH               14
  MEM_STATIC           500
  MEM_TOTAL            32000
$end

@@@

$comment
  IRC connecting the two structures.
$end

$molecule
  0   1
  Fe
  C   1   rFeC_Head
  X1  1   rFeC_Legs  2  a_90
  C   1   rFeC_Legs  2  a_CH_CL     3 d_90
  C   1   rFeC_Legs  2  a_nCH_CL    3 d_90
  X2  1   rFeO_Legs  2  a_90        3 d_0
  O   1   rFeO_Head  2  a_0         3 d_0
  O   1   rFeO_Legs  7  a_OL_Fe_OH  6 d_90
  O   1   rFeO_Legs  7  a_nOL_Fe_OH 6 d_90

  rFeC_Head   =    1.85674
  rFeC_Legs   =    1.85118
  rFeO_Head   =    2.99827
  rFeO_Legs   =    2.98752
  a_nCH_CL    = -108.48350
  a_CH_CL     =  108.48350
  a_nOL_Fe_OH = -105.21160
  a_OL_Fe_OH  =  105.21160
  a_0         =    0.00000
  a_90        =   90.00000
  d_0         =    0.00000
  d_90        =   90.00000
$end

$rem
  JOBTYPE                RPATH
  METHOD                 wB97M-V   
  UNRESTRICTED           FALSE
  BASIS                  PCSEG-1
  SYMMETRY               FALSE
  SYM_IGNORE             TRUE
  GEN_SCFMAN             TRUE
  SCF_ALGORITHM          DIIS_GDM
  SCF_CONVERGENCE        8
  SCF_GUESS              READ
  MAX_SCF_CYCLES         2000
  GEOM_OPT_HESSIAN       READ
  RPATH_COORDS           2
  RPATH_MAX_CYCLES       200
  RPATH_TOL_DISPLACEMENT 500
  RPATH_PRINT            10
  GUI                    2
  THRESH                 14
  MEM_STATIC             500
  MEM_TOTAL              32000
$end

Output

                  Welcome to Q-Chem
     A Quantum Leap Into The Future Of Chemistry


 Q-Chem 6.1 (devel), Q-Chem, Inc., Pleasanton, CA (2022)

 Checking the input file for inconsistencies... 	...done.

--------------------------------------------------------------
User input:
--------------------------------------------------------------
$comment
  Frequency calculation on it.
$end

$molecule
  0   1
  Fe
  C   1   rFeC_Head
  X1  1   rFeC_Legs  2  a_90
  C   1   rFeC_Legs  2  a_CH_CL     3 d_90
  C   1   rFeC_Legs  2  a_nCH_CL    3 d_90
  X2  1   rFeO_Legs  2  a_90        3 d_0
  O   1   rFeO_Head  2  a_0         3 d_0
  O   1   rFeO_Legs  7  a_OL_Fe_OH  6 d_90
  O   1   rFeO_Legs  7  a_nOL_Fe_OH 6 d_90

  rFeC_Head   =    1.85674
  rFeC_Legs   =    1.85118
  rFeO_Head   =    2.99827
  rFeO_Legs   =    2.98752
  a_nCH_CL    = -108.48350
  a_CH_CL     =  108.48350
  a_nOL_Fe_OH = -105.21160
  a_OL_Fe_OH  =  105.21160
  a_0         =    0.00000
  a_90        =   90.00000
  d_0         =    0.00000
  d_90        =   90.00000
$end

$rem
  JOBTYPE              FREQ
  METHOD               wB97M-V   
  UNRESTRICTED         FALSE
  BASIS                PCSEG-1
  SYMMETRY             FALSE
  SYM_IGNORE           TRUE
  GEN_SCFMAN           TRUE
  SCF_ALGORITHM        DIIS_GDM
  SCF_CONVERGENCE      8
  MAX_SCF_CYCLES       200
  MAX_SCF_CYCLES       2000
  THRESH               14
  MEM_STATIC           500
  MEM_TOTAL            32000
$end

--------------------------------------------------------------
 ----------------------------------------------------------------
             Standard Nuclear Orientation (Angstroms)
    I     Atom           X                Y                Z
 ----------------------------------------------------------------
    1      Fe      0.0000000000     0.0000000000     0.0000000000
    2      C       0.0000000000     0.0000000000     1.8567400000
    3      C       0.0000000000    -1.7556868669    -0.5868824567
    4      C      -0.0000000000     1.7556868669    -0.5868824567
    5      O       0.0000000000     0.0000000000     2.9982700000
    6      O       0.0000000000    -2.8828474339    -0.7838790871
    7      O      -0.0000000000     2.8828474339    -0.7838790871
 ----------------------------------------------------------------
 Nuclear Repulsion Energy =         385.56084442 hartrees
 There are       34 alpha and       34 beta electrons
 Requested basis set is pcseg-1
 There are 47 shells and 115 basis functions

 Total QAlloc Memory Limit  32000 MB
 Mega-Array Size       489 MB
 MEM_STATIC part       500 MB


                       Distance Matrix (Angstroms)
             Fe(  1)   C (  2)   C (  3)   C (  4)   O (  5)   O (  6)
   C (  2)  1.856740
   C (  3)  1.851180  3.008941
   C (  4)  1.851180  3.008941  3.511374
   O (  5)  2.998270  1.141530  3.991961  3.991961
   O (  6)  2.987520  3.909435  1.144246  4.642716  4.755572
   O (  7)  2.987520  3.909435  4.642716  1.144246  4.755572  5.765695

 
 A cutoff of  1.0D-14 yielded   1020 shell pairs
 There are      6284 function pairs (      7565 Cartesian)
 Smallest overlap matrix eigenvalue = 6.32E-03
 Guess from superposition of atomic densities
 Warning:  Energy on first SCF cycle will be non-variational
 SAD guess density has 68.000000 electrons

 -----------------------------------------------------------------------
  General SCF calculation program by
  Eric Jon Sundstrom, Paul Horn, Yuezhi Mao, Dmitri Zuev, Alec White,
  David Stuck, Shaama M.S., Shane Yost, Joonho Lee, David Small,
  Daniel Levine, Susi Lehtola, Hugh Burton, Evgeny Epifanovsky,
  Bang C. Huynh
 -----------------------------------------------------------------------
 Exchange:     0.1500 Hartree-Fock + 1.0000 wB97M-V + LR-HF
 Correlation:  1.0000 wB97M-V
 Using SG-2 standard quadrature grid
 Nonlocal Correlation:  VV10 with C = 0.0100 and b = 6.00 and scale = 1.00000
 Grid used for NLC:  SG-1 standard quadrature
 using 32 threads for integral computing
 -------------------------------------------------------
 OpenMP Integral computing Module                
 Release: version 1.0, May 2013, Q-Chem Inc. Pittsburgh 
 -------------------------------------------------------
 A restricted SCF calculation will be
 performed using DIIS, GDM
 SCF converges when RMS gradient is below 1.0e-08
 ---------------------------------------
  Cycle       Energy         DIIS error
 ---------------------------------------
    1   -1603.9852374029      7.89e-02  
    2   -1602.9299958280      1.61e-02  
    3   -1597.1826902850      6.63e-02  
    4   -1603.1172321944      1.10e-02  
    5   -1603.2523387081      2.44e-03  Done DIIS. Switching to GDM
 ---------------------------------------
  Cycle       Energy        RMS Gradient
 ---------------------------------------
    1   -1603.2523387081      3.38e-02   Normal BFGS step
    2   -1603.2431135474      6.83e-02  Line search: overstep
    3   -1603.2599596578      2.21e-02   Normal BFGS step
    4   -1603.2597165902      5.94e-02  Line search: overstep
    5   -1603.2618854233      3.17e-02   Normal BFGS step
    6   -1603.2666877931      2.38e-02   Normal BFGS step
    7   -1603.2708571972      2.09e-02   Normal BFGS step
    8   -1603.2765658446      3.73e-02   Normal BFGS step
    9   -1603.2815936666      2.50e-02   Normal BFGS step
   10   -1603.2875115885      1.13e-02   Normal BFGS step
   11   -1603.2883917446      1.09e-02   Normal BFGS step
   12   -1603.2889452516      2.86e-03   Normal BFGS step
   13   -1603.2890324357      2.01e-03   Normal BFGS step
   14   -1603.2890545413      1.63e-03   Normal BFGS step
   15   -1603.2890590967      4.33e-04   Normal BFGS step
   16   -1603.2890602614      2.88e-04   Normal BFGS step
   17   -1603.2890606168      1.27e-04   Normal BFGS step
   18   -1603.2890607169      1.27e-04   Normal BFGS step
   19   -1603.2890607455      4.19e-05   Normal BFGS step
   20   -1603.2890607532      1.63e-05   Normal BFGS step
   21   -1603.2890607548      7.11e-06   Normal BFGS step
   22   -1603.2890607550      2.79e-06   Normal BFGS step
   23   -1603.2890607550      1.08e-06   Normal BFGS step
   24   -1603.2890607550      4.47e-07   Normal BFGS step
   25   -1603.2890607550      2.23e-07   Normal BFGS step
   26   -1603.2890607550      8.83e-08   Normal BFGS step
   27   -1603.2890607550      1.17e-08   Normal BFGS step
   28   -1603.2890607550      5.50e-09  Convergence criterion met
 ---------------------------------------
 SCF time:   CPU 1312.74s  wall 50.00s 
 SCF   energy in the final basis set =    -1603.2890607550
 Total energy in the final basis set =    -1603.2890607550
 
 --------------------------------------------------------------
 
                    Orbital Energies (a.u.)
 --------------------------------------------------------------
 
 Alpha MOs
 -- Occupied --
******** -30.2116 -26.0147 -26.0110 -25.9874 -19.4309 -19.4168 -19.4168
-10.4839 -10.4718 -10.4718  -3.5750  -2.3498  -2.3473  -2.3146  -1.2949
 -1.2795  -1.2794  -0.7087  -0.6929  -0.6867  -0.5983  -0.5910  -0.5892
 -0.5764  -0.5732  -0.5728  -0.5718  -0.5596  -0.5394  -0.3981  -0.3632
 -0.3390  -0.2992
 -- Virtual --
 -0.0229  -0.0181   0.0696   0.0722   0.0761   0.0890   0.0944   0.1011
  0.2466   0.2816   0.3041   0.3085   0.4248   0.4533   0.4857   0.4987
  0.5010   0.5214   0.5369   0.5560   0.5933   0.6919   0.7076   0.7191
  0.7218   0.7679   0.7909   0.8046   0.8090   0.8318   0.8908   1.0110
  1.0156   1.0268   1.0285   1.0299   1.0728   1.0903   1.1465   1.2334
  1.3291   1.6523   1.6633   1.6687   1.6694   1.6694   1.6777   1.6932
  1.7183   1.7711   1.8114   1.8149   1.8386   1.8406   1.9133   1.9268
  2.3320   2.3342   2.3445   2.3452   2.3464   2.3472   2.6171   2.6362
  2.6569   2.9103   2.9194   2.9212   2.9410   2.9755   2.9886   3.2704
  3.3035   3.3219   4.0074   4.0108   4.0384   4.0458   4.0948   4.2029
  4.2292
 --------------------------------------------------------------
 
          Ground-State Mulliken Net Atomic Charges

     Atom                 Charge (a.u.)
  ----------------------------------------
      1 Fe                   -0.304076
      2 C                     0.287190
      3 C                     0.238545
      4 C                     0.238545
      5 O                    -0.148713
      6 O                    -0.155745
      7 O                    -0.155745
  ----------------------------------------
  Sum of atomic charges =     0.000000
 -----------------------------------------------------------------
 Calculating MO derivatives via CPSCF
    1     0    24    0.0572420  
    2     0    24    0.0210925  
    3     0    24    0.0082880  
    4     0    24    0.0047557  
    5     0    24    0.0030858  
    6     0    24    0.0005978  
    7     0    24    0.0000770  
    8     9    15    0.0000101  
    9    20     4    0.0000014  
   10    24     0    0.0000002  Converged
 Polarizability Matrix (a.u.)
            1           2           3
    1 -33.9135482   0.0000000  -0.0000000
    2   0.0000000-101.2404509   0.0000000
    3  -0.0000000   0.0000000 -71.7587828
 Calculating analytic Hessian of the SCF energy
 
 Direct stationary perturbation theory relativistic correction:
 
 rels  =       4.907519189375
 relv  =     -17.041773447204
 rel2e =       0.000000000000
 E_rel =     -12.134254257829
 
 **********************************************************************
 **                                                                  **
 **                       VIBRATIONAL ANALYSIS                       **
 **                       --------------------                       **
 **                                                                  **
 **        VIBRATIONAL FREQUENCIES (CM**-1) AND NORMAL MODES         **
 **     FORCE CONSTANTS (mDYN/ANGSTROM) AND REDUCED MASSES (AMU)     **
 **                  INFRARED INTENSITIES (KM/MOL)                   **
 **                                                                  **
 **********************************************************************
 

 Mode:                 1                      2                      3
 Frequency:       -77.25                  77.55                  82.92
 Force Cnst:      0.0624                 0.0586                 0.0928
 Red. Mass:      17.7469                16.5303                22.9146
 IR Active:          YES                    YES                    YES
 IR Intens:        0.586                  0.295                  4.946
 Raman Active:       YES                    YES                    YES
               X      Y      Z        X      Y      Z        X      Y      Z
 Fe         0.000 -0.000 -0.257    0.000 -0.160  0.000    0.418  0.000  0.000
 C          0.000  0.000 -0.271    0.000  0.207  0.000    0.119 -0.000  0.000
 C         -0.000 -0.160  0.223   -0.000 -0.117 -0.159   -0.015  0.000  0.000
 C         -0.000  0.160  0.223   -0.000 -0.117  0.159   -0.015  0.000 -0.000
 O         -0.000  0.000 -0.276   -0.000  0.729  0.000   -0.364 -0.000  0.000
 O         -0.000 -0.208  0.523   -0.000 -0.075 -0.394   -0.582  0.000  0.000
 O         -0.000  0.208  0.523   -0.000 -0.075  0.394   -0.582  0.000 -0.000
 TransDip   0.000 -0.000  0.025    0.000 -0.017 -0.000    0.071  0.000 -0.000

 Mode:                 4                      5                      6
 Frequency:       265.50                 284.91                 340.16
 Force Cnst:      0.5299                 0.6069                 0.8930
 Red. Mass:      12.7599                12.6899                13.0982
 IR Active:          YES                    YES                    YES
 IR Intens:        6.127                  0.000                  5.154
 Raman Active:       YES                    YES                    YES
               X      Y      Z        X      Y      Z        X      Y      Z
 Fe         0.009 -0.000 -0.000    0.000  0.000  0.000   -0.000 -0.082 -0.000
 C          0.714 -0.000  0.000   -0.000  0.000  0.000   -0.000 -0.447  0.000
 C         -0.388  0.000 -0.000   -0.643 -0.000  0.000   -0.000  0.196 -0.508
 C         -0.388  0.000  0.000    0.643 -0.000 -0.000    0.000  0.196  0.508
 O         -0.350  0.000  0.000    0.000 -0.000  0.000    0.000  0.218  0.000
 O          0.183 -0.000 -0.000    0.294 -0.000 -0.000    0.000  0.055  0.271
 O          0.183 -0.000 -0.000   -0.294  0.000  0.000   -0.000  0.055 -0.271
 TransDip   0.079 -0.000  0.000   -0.000 -0.000 -0.000   -0.000  0.073  0.000

 Mode:                 7                      8                      9
 Frequency:       375.66                 413.91                 417.04
 Force Cnst:      1.1122                 1.4876                 1.4474
 Red. Mass:      13.3762                14.7381                14.1243
 IR Active:          YES                    YES                    YES
 IR Intens:       15.709                  0.091                  0.041
 Raman Active:       YES                    YES                    YES
               X      Y      Z        X      Y      Z        X      Y      Z
 Fe         0.000  0.000 -0.010   -0.000  0.000 -0.151   -0.201 -0.000  0.000
 C         -0.000  0.000  0.030    0.000 -0.000  0.500    0.566 -0.000 -0.000
 C         -0.000 -0.383  0.426    0.000 -0.171 -0.343    0.525  0.000  0.000
 C         -0.000  0.383  0.426    0.000  0.171 -0.343    0.525 -0.000  0.000
 O          0.000 -0.000  0.021   -0.000  0.000  0.529   -0.192  0.000 -0.000
 O          0.000 -0.258 -0.324   -0.000 -0.268  0.070   -0.159  0.000 -0.000
 O          0.000  0.258 -0.324   -0.000  0.268  0.070   -0.159 -0.000 -0.000
 TransDip  -0.000 -0.000  0.127   -0.000 -0.000  0.010   -0.007  0.000 -0.000

 Mode:                10                     11                     12
 Frequency:       459.41                 471.13                 497.81
 Force Cnst:      2.1896                 2.3401                 2.0500
 Red. Mass:      17.6080                17.8941                14.0401
 IR Active:          YES                    YES                    YES
 IR Intens:       94.366                 95.198                 54.832
 Raman Active:       YES                    YES                    YES
               X      Y      Z        X      Y      Z        X      Y      Z
 Fe         0.000  0.000  0.309   -0.000  0.325 -0.000   -0.000 -0.194  0.000
 C         -0.000  0.000 -0.334    0.000  0.239  0.000    0.000  0.840  0.000
 C         -0.000 -0.239 -0.404    0.000 -0.304 -0.411    0.000  0.130 -0.252
 C         -0.000  0.239 -0.404    0.000 -0.304  0.411    0.000  0.130  0.252
 O          0.000 -0.000 -0.327   -0.000 -0.074  0.000   -0.000 -0.270  0.000
 O          0.000 -0.346  0.051   -0.000 -0.393  0.016   -0.000  0.062  0.089
 O          0.000  0.346  0.051   -0.000 -0.393 -0.016   -0.000  0.062 -0.089
 TransDip   0.000 -0.000 -0.311   -0.000 -0.312  0.000    0.000  0.237 -0.000

 Mode:                13                     14                     15
 Frequency:      2095.19                2115.41                2193.46
 Force Cnst:     34.7061                35.3213                37.7901
 Red. Mass:      13.4186                13.3967                13.3311
 IR Active:          YES                    YES                    YES
 IR Intens:     2228.434               1064.626                 47.724
 Raman Active:       YES                    YES                    YES
               X      Y      Z        X      Y      Z        X      Y      Z
 Fe         0.000 -0.002  0.000    0.000  0.000 -0.003    0.000 -0.000  0.003
 C         -0.000 -0.006 -0.000    0.000 -0.000  0.617    0.000  0.000  0.519
 C         -0.000  0.558  0.106   -0.000  0.362  0.062    0.000 -0.436 -0.093
 C         -0.000  0.558 -0.106    0.000 -0.362  0.062   -0.000  0.436 -0.093
 O          0.000  0.002  0.000   -0.000  0.000 -0.457   -0.000 -0.000 -0.372
 O          0.000 -0.415 -0.076   -0.000 -0.261 -0.044   -0.000  0.307  0.056
 O          0.000 -0.415  0.076   -0.000  0.261 -0.044   -0.000 -0.307  0.056
 TransDip  -0.000  1.512 -0.000    0.000  0.000  1.045    0.000 -0.000  0.221

 STANDARD THERMODYNAMIC QUANTITIES AT   298.15 K  AND     1.00 ATM

   This Molecule has  1 Imaginary Frequencies
   Zero point vibrational energy:       14.424 kcal/mol

   Atom    1 Element Fe Has Mass   55.93490
   Atom    2 Element C  Has Mass   12.00000
   Atom    3 Element C  Has Mass   12.00000
   Atom    4 Element C  Has Mass   12.00000
   Atom    5 Element O  Has Mass   15.99491
   Atom    6 Element O  Has Mass   15.99491
   Atom    7 Element O  Has Mass   15.99491
   Molecular Mass:   139.919630 amu
   Principal axes and moments of inertia in amu*Bohr^2:
                             1           2           3
    Eigenvalues --      736.27790  1213.58984  1949.86774
          X               0.00000     0.00000     1.00000
          Y               1.00000     0.00000     0.00000
          Z               0.00000     1.00000     0.00000
   Rotational Symmetry Number is   1
   The Molecule is an Asymmetric Top
   Translational Enthalpy:        0.889 kcal/mol
   Rotational Enthalpy:           0.889 kcal/mol
   Vibrational Enthalpy:         17.233 kcal/mol
   gas constant (RT):             0.592 kcal/mol
   Translational Entropy:        40.719  cal/mol.K
   Rotational Entropy:           28.945  cal/mol.K
   Vibrational Entropy:          17.153  cal/mol.K

   Total Enthalpy:               19.603 kcal/mol
   Total Entropy:                86.818  cal/mol.K

   Quasi-RRHO corrections using alpha = 4, and omega = 100 cm^-1
   QRRHO-Vib. Enthalpy:          16.779 kcal/mol
   QRRHO-Vib. Entropy:           16.025  cal/mol.K
   QRRHO-Total Enthalpy:         19.148 kcal/mol
   QRRHO-Total Entropy:          85.690  cal/mol.K
 Total job time:  245.54s(wall), 7204.69s(cpu) 
 Tue Jun 11 07:12:04 2024

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User input: 2 of 2 
 
                  Welcome to Q-Chem
     A Quantum Leap Into The Future Of Chemistry


 Q-Chem 6.1 (devel), Q-Chem, Inc., Pleasanton, CA (2022)


 Checking the input file for inconsistencies... 	...done.

--------------------------------------------------------------
User input:
--------------------------------------------------------------

$comment
  IRC connecting the two structures.
$end

$molecule
  0   1
  Fe
  C   1   rFeC_Head
  X1  1   rFeC_Legs  2  a_90
  C   1   rFeC_Legs  2  a_CH_CL     3 d_90
  C   1   rFeC_Legs  2  a_nCH_CL    3 d_90
  X2  1   rFeO_Legs  2  a_90        3 d_0
  O   1   rFeO_Head  2  a_0         3 d_0
  O   1   rFeO_Legs  7  a_OL_Fe_OH  6 d_90
  O   1   rFeO_Legs  7  a_nOL_Fe_OH 6 d_90

  rFeC_Head   =    1.85674
  rFeC_Legs   =    1.85118
  rFeO_Head   =    2.99827
  rFeO_Legs   =    2.98752
  a_nCH_CL    = -108.48350
  a_CH_CL     =  108.48350
  a_nOL_Fe_OH = -105.21160
  a_OL_Fe_OH  =  105.21160
  a_0         =    0.00000
  a_90        =   90.00000
  d_0         =    0.00000
  d_90        =   90.00000
$end

$rem
  JOBTYPE                RPATH
  METHOD                 wB97M-V   
  UNRESTRICTED           FALSE
  BASIS                  PCSEG-1
  SYMMETRY               FALSE
  SYM_IGNORE             TRUE
  GEN_SCFMAN             TRUE
  SCF_ALGORITHM          DIIS_GDM
  SCF_CONVERGENCE        8
  SCF_GUESS              READ
  MAX_SCF_CYCLES         2000
  GEOM_OPT_HESSIAN       READ
  RPATH_COORDS           2
  RPATH_MAX_CYCLES       200
  RPATH_TOL_DISPLACEMENT 500
  RPATH_PRINT            10
  GUI                    2
  THRESH                 14
  MEM_STATIC             500
  MEM_TOTAL              32000
$end

--------------------------------------------------------------
 ----------------------------------------------------------------
             Standard Nuclear Orientation (Angstroms)
    I     Atom           X                Y                Z
 ----------------------------------------------------------------
    1      Fe      0.0000000000     0.0000000000     0.0000000000
    2      C       0.0000000000     0.0000000000     1.8567400000
    3      C       0.0000000000    -1.7556868669    -0.5868824567
    4      C      -0.0000000000     1.7556868669    -0.5868824567
    5      O       0.0000000000     0.0000000000     2.9982700000
    6      O       0.0000000000    -2.8828474339    -0.7838790871
    7      O      -0.0000000000     2.8828474339    -0.7838790871
 ----------------------------------------------------------------
 Nuclear Repulsion Energy =         385.56084442 hartrees
 There are       34 alpha and       34 beta electrons
 Requested basis set is pcseg-1
 There are 47 shells and 115 basis functions

 Total QAlloc Memory Limit  32000 MB
 Mega-Array Size       489 MB
 MEM_STATIC part       500 MB

 Starting direction for rxn path = 1

                       Distance Matrix (Angstroms)
             Fe(  1)   C (  2)   C (  3)   C (  4)   O (  5)   O (  6)
   C (  2)  1.856740
   C (  3)  1.851180  3.008941
   C (  4)  1.851180  3.008941  3.511374
   O (  5)  2.998270  1.141530  3.991961  3.991961
   O (  6)  2.987520  3.909435  1.144246  4.642716  4.755572
   O (  7)  2.987520  3.909435  4.642716  1.144246  4.755572  5.765695

 
 A cutoff of  1.0D-14 yielded   1020 shell pairs
 There are      6284 function pairs (      7565 Cartesian)
 Smallest overlap matrix eigenvalue = 6.32E-03

 Scale SEOQF with 1.000000e+00/1.000000e-01/1.000000e-01

 Standard Electronic Orientation quadrupole field applied
 Nucleus-field energy     =     0.0000000007 hartrees
 Guess MOs from SCF MO coefficient file

 -----------------------------------------------------------------------
  General SCF calculation program by
  Eric Jon Sundstrom, Paul Horn, Yuezhi Mao, Dmitri Zuev, Alec White,
  David Stuck, Shaama M.S., Shane Yost, Joonho Lee, David Small,
  Daniel Levine, Susi Lehtola, Hugh Burton, Evgeny Epifanovsky,
  Bang C. Huynh
 -----------------------------------------------------------------------
 Exchange:     0.1500 Hartree-Fock + 1.0000 wB97M-V + LR-HF
 Correlation:  1.0000 wB97M-V
 Using SG-2 standard quadrature grid
 Nonlocal Correlation:  VV10 with C = 0.0100 and b = 6.00 and scale = 1.00000
 Grid used for NLC:  SG-1 standard quadrature
 using 32 threads for integral computing
 -------------------------------------------------------
 OpenMP Integral computing Module                
 Release: version 1.0, May 2013, Q-Chem Inc. Pittsburgh 
 -------------------------------------------------------
 A restricted SCF calculation will be
 performed using DIIS, GDM
 SCF converges when RMS gradient is below 1.0e-08
 ---------------------------------------
  Cycle       Energy         DIIS error
 ---------------------------------------
    1   -1603.2890607580      4.45e-10  
    2   -1603.2890607580      1.31e-09  Done DIIS. Switching to GDM
 ---------------------------------------
  Cycle       Energy        RMS Gradient
 ---------------------------------------
    1   -1603.2890607580      4.09e-08   Normal BFGS step
    2   -1603.2890607580      1.40e-07   Normal BFGS step
    3   -1603.2890607580      4.51e-09  Convergence criterion met
 ---------------------------------------
 SCF time:   CPU 199.47s  wall 8.00s 
 SCF   energy in the final basis set =    -1603.2890607580
 Total energy in the final basis set =    -1603.2890607580
 
 --------------------------------------------------------------
 
                    Orbital Energies (a.u.)
 --------------------------------------------------------------
 
 Alpha MOs
 -- Occupied --
******** -30.2116 -26.0147 -26.0110 -25.9874 -19.4309 -19.4168 -19.4168
-10.4839 -10.4718 -10.4718  -3.5750  -2.3498  -2.3473  -2.3146  -1.2949
 -1.2795  -1.2794  -0.7087  -0.6929  -0.6867  -0.5983  -0.5910  -0.5892
 -0.5764  -0.5732  -0.5728  -0.5718  -0.5596  -0.5394  -0.3981  -0.3632
 -0.3390  -0.2992
 -- Virtual --
 -0.0229  -0.0181   0.0696   0.0722   0.0761   0.0890   0.0944   0.1011
  0.2466   0.2816   0.3041   0.3085   0.4248   0.4533   0.4857   0.4987
  0.5010   0.5214   0.5369   0.5560   0.5933   0.6919   0.7076   0.7191
  0.7218   0.7679   0.7909   0.8046   0.8090   0.8318   0.8908   1.0110
  1.0156   1.0268   1.0285   1.0299   1.0728   1.0903   1.1465   1.2334
  1.3291   1.6523   1.6633   1.6687   1.6694   1.6694   1.6777   1.6932
  1.7183   1.7711   1.8114   1.8149   1.8386   1.8406   1.9133   1.9268
  2.3320   2.3342   2.3445   2.3452   2.3464   2.3472   2.6171   2.6362
  2.6569   2.9103   2.9194   2.9212   2.9410   2.9755   2.9886   3.2704
  3.3035   3.3219   4.0074   4.0108   4.0384   4.0458   4.0948   4.2029
  4.2292
 --------------------------------------------------------------
 
          Ground-State Mulliken Net Atomic Charges

     Atom                 Charge (a.u.)
  ----------------------------------------
      1 Fe                   -0.304076
      2 C                     0.287190
      3 C                     0.238545
      4 C                     0.238545
      5 O                    -0.148713
      6 O                    -0.155745
      7 O                    -0.155745
  ----------------------------------------
  Sum of atomic charges =     0.000000

 Calculating analytic gradient of the SCF energy
 Gradient of SCF Energy
            1           2           3           4           5           6
    1  -0.0000000  -0.0000000   0.0000000  -0.0000000   0.0000000  -0.0000000
    2   0.0000000   0.0000000  -0.0000090   0.0000090  -0.0000000   0.0000080
    3   0.0000014  -0.0000030  -0.0000033  -0.0000033   0.0000040   0.0000021
            7
    1   0.0000000
    2  -0.0000080
    3   0.0000021
 Max gradient component =       8.956E-06
 RMS gradient           =       4.064E-06
 Gradient time:  CPU 66.10 s  wall 3.20 s
 ------------------------------------------------------------------------
 Reaction path following.  The coordinates are z-matrix               
 Step   1 E=   -1603.289061 |G|=  0.000019 S_lin= 0.0000 S_tot= 0.0000
 ------------------------------------------------------------------------
 IRC -- neg. force constant =  -4.316797616690993E-003
 IRC -- max trans/rot const =   3.328729052861884E-004
 First IRC step, with rxn. path sign =            1

 Q-Chem fatal error occurred in module 0, line  122:

 First_IRC_step: Illegal value of coordinates

Provided a different Z-Matrix coming out of the optimization that doesn’t have dummy atoms.

$molecule
  0   1
  Fe
  C  1 1.851175
  O  2 1.144250 1 171.431191
  C  1 1.851175 2 143.032353 3  180.000000 
  O  4 1.144250 1 171.431191 2 -180.000000 
  C  1 1.856740 2 108.483824 3   -0.000000 
  O  6 1.141528 1 179.999999 2    0.000000 
$end

Still same error.

By the way, the calculation runs with Cartesian coordinates. It takes too long to reach the minima so I wanted to try with Z-Matrix to see what happens…