Failure in Frequency job

Questions
#1

Hi, I’m encountering an issue with a Q-Chem Frequency job where the calculation fails during the CPCM-SWIG Hessian step. The output shows a “Singularity detected in AXeqB” warning, followed by a fatal error: *“Unable to find relaxed density.” I am sharing my input file. Can anyone help me with this?
" Warning: Singularity detected in AXeqB0 147 8 1
0.000000000000000E+000 176

Q-Chem fatal error occurred in module 0, line 118:

Unable to find relaxed density"
Input file:
$molecule
0 1
H 0.14405000 -2.17419000 -3.23646000
C 0.07767000 -1.20685000 -3.70221000
C 0.00000000 -0.00000000 -2.95904000
C -0.07767000 1.20685000 -3.70221000
H -0.14405000 2.17419000 -3.23646000
C -0.07787000 1.20070000 -5.10016000
H -0.13949000 2.13475000 -5.64413000
C 0.00000000 -0.00000000 -5.79822000
H 0.00000000 -0.00000000 -6.88062000
C 0.07787000 -1.20070000 -5.10016000
H 0.13949000 -2.13475000 -5.64413000
C 0.00000000 -0.00000000 -1.44082000
C -0.00064000 1.20096000 -0.69881000
C 0.00064000 1.20096000 0.69881000
C -0.00000000 0.00000000 1.44082000
C -0.00064000 -1.20096000 0.69881000
C 0.00064000 -1.20096000 -0.69881000
C -0.00000000 0.00000000 2.95904000
C 0.07767000 1.20685000 3.70221000
C 0.07787000 1.20070000 5.10016000
C -0.00000000 0.00000000 5.79822000
C -0.07787000 -1.20070000 5.10016000
C -0.07767000 -1.20685000 3.70221000
H 0.00198000 2.16916000 -1.16800000
H -0.00198000 2.16916000 1.16800000
H 0.00198000 -2.16916000 1.16800000
H -0.00198000 -2.16916000 -1.16800000
H 0.14405000 2.17419000 3.23646000
H 0.13949000 2.13475000 5.64413000
H -0.00000000 0.00000000 6.88062000
H -0.13949000 -2.13475000 5.64413000
H -0.14405000 -2.17419000 3.23646000
$end

$rem
JOB_TYPE Optimization
METHOD wB97X-D
BASIS aug-cc-pvDZ
SCF_CONVERGENCE 8
SCF_MAX_CYCLES 200
GEOM_OPT_MAX_CYCLES 200
GEOM_OPT_DMAX 300
SYMMETRY FALSE
SYM_IGNORE TRUE
GUI 2
SOLVENT_METHOD PCM
$end

$pcm
THEORY CPCM
$end

$solvent
DIELECTRIC 37.5
OPTICALDIELECTRIC 1.8068
$end

@@@

$molecule
read
$end

$rem
JOB_TYPE Freq
METHOD wB97X-D
BASIS aug-cc-pvDZ
SCF_CONVERGENCE 8
VIBMAN_PRINT 4
SCF_MAX_CYCLES 200
GEOM_OPT_MAX_CYCLES 200
SYMMETRY FALSE
SYM_IGNORE TRUE
MEM_TOTAL 248000
MEM_STATIC 4000
SOLVENT_METHOD PCM
$end

$pcm
THEORY CPCM
$end

$solvent
DIELECTRIC 37.5
OPTICALDIELECTRIC 1.8068
$end

#2

If Q-Chem is trying to compute the relaxed density, then that is probably not the “CPCM-SWIG Hessian step” (i.e., has nothing to do with the solvation model). Please post the end of the output where the error occurs.

#3 
          Cartesian Multipole Moments
 -----------------------------------------------------------------
    Charge (ESU x 10^10)
                -0.0000
    Dipole Moment (Debye)
         X       0.0000      Y      -0.0000      Z       0.0000
       Tot       0.0000
    Quadrupole Moments (Debye-Ang)
        XX    -108.0345     XY       0.0000     YY     -95.5743
        XZ      -0.0000     YZ      -0.0000     ZZ     -87.6642
    Octopole Moments (Debye-Ang^2)
       XXX       0.0000    XXY      -0.0000    XYY      -0.0000
       YYY      -0.0000    XXZ       0.0000    XYZ      40.9718
       YYZ      -0.0000    XZZ       0.0000    YZZ      -0.0000
       ZZZ      -0.0000
    Hexadecapole Moments (Debye-Ang^3)
      XXXX    -349.5469   XXXY      -0.0000   XXYY    -154.1029
      XYYY      -0.0000   YYYY    -640.8472   XXXZ       0.0000
      XXYZ       0.0000   XYYZ       0.0000   YYYZ       0.0000
      XXZZ   -1539.3186   XYZZ       0.0000   YYZZ   -1513.1283
      XZZZ       0.0000   YZZZ       0.0000   ZZZZ   -7511.3828
 -----------------------------------------------------------------
 Calculating MO derivatives via CPSCF
 Computing fast CPCM-SWIG hessian.
   1         3          96      1.055759    0.030294
   2         3          96      0.290818    0.008684
   3         3          96      0.039318    0.001658
   4         3          96      0.006291    0.000285
   5         8          91      0.000837    0.000036
   6        54          45      0.000079    0.000004    Collapsing Subspace
   7        69          30      0.000043    0.000003
 Warning:  Singularity detected in AXeqB0         145           8           1
  0.000000000000000E+000         174

 Q-Chem fatal error occurred in module 0, line  118:

 Unable to find relaxed density

Error in Q-Chem run part 2
remove work dirs /scratch1/hsaha/scratch/qchem/qchem1733275.0 -- /scratch1/hsaha/scratch/qchem/qchem1733275.0
rm -rf /scratch1/hsaha/scratch/qchem/qchem1733275.0
rm -rf /scratch1/hsaha/scratch/qchem/qchem1733275
Error in the Q-Chem run

That’s the message from the output file.

#4

The CPCM-SWIG Hessian calculation is complete, what you are seeing is a failure of the CPSCF iterations to compute the relaxed density. The reason isn’t entirely clear to me but this calculation does give warnings about linear dependencies and settings for THRESH and S2THRESH. You should take those warnings seriously.

If you want the linear dependency problem to go away entirely then discard the diffuse functions, which are unlikely to change the ground-state vibrational frequencies. (Indeed, 6-31G* is likely a perfectly adequate basis set for this functional.) The wB97X-D/6-31G* optimization and frequency calculation run successfully for me in just a few minutes.