Error in constrained geometry optimization

Questions
#1

I am running constrained geometry optimization on the following coronene. The following is my input and the error. If anyone has an idea on how to resolve it.

$molecule
1 1
C 1.22127 0.70510 0.00000
C 1.22127 -0.70510 0.00000
C 0.00000 1.41021 0.00000
C 2.44340 1.41070 0.00000
C -0.00000 -1.41021 -0.00000
C -1.22127 0.70510 -0.00000
C 2.44340 -1.41070 0.00000
C 0.00000 2.82140 0.00000
C 3.65444 0.70022 0.00000
C 2.43363 2.81472 0.00000
C 3.65444 -0.70022 0.00000
C -1.22127 -0.70510 -0.00000
C 1.22081 3.51495 0.00000
C -0.00000 -2.82140 -0.00000
C -2.44340 1.41070 -0.00000
C 2.43363 -2.81472 0.00000
C -1.22081 3.51495 -0.00000
C -2.44340 -1.41070 -0.00000
C 1.22081 -3.51495 0.00000
C -2.43363 2.81472 -0.00000
C -1.22081 -3.51495 -0.00000
C -3.65444 0.70022 -0.00000
C -2.43363 -2.81472 -0.00000
C -3.65444 -0.70022 -0.00000
H 4.59989 1.22945 0.00000
H 3.36468 3.36890 0.00000
H 4.59989 -1.22945 0.00000
H 1.23521 4.59835 0.00000
H 3.36468 -3.36890 0.00000
H -1.23521 4.59835 -0.00000
H 1.23521 -4.59835 0.00000
H -3.36468 3.36890 -0.00000
H -1.23521 -4.59835 -0.00000
H -4.59989 1.22945 -0.00000
H -3.36468 -3.36890 -0.00000
H -4.59989 -1.22945 -0.00000
H 0 0 0.7
$end

$rem
BASIS = aug-cc-pVDZ
SYMMETRY = TRUE
JOBTYPE = OPT
MAX_SCF_CYCLES = 100
METHOD = B3LYP
SCF_ALGORITHM = GDM
SCF_CONVERGENCE = 8
THRESH = 14
SYM_IGNORE = 1
XC_GRID = 000099000302
$end

$OPT
CONSTRAINT
STRE 1 37 1.41021
STRE 2 37 1.41021
STRE 3 37 1.41021
STRE 5 37 1.41021
STRE 6 37 1.41021
STRE 12 37 1.41021
ENDCONSTRAINT
$end

$OPT
FIXED
4 XYZ
7:11 XYZ
13:36 XYZ
ENDFIXED
$end
The error:
Translations and Rotations Projected Out of Hessian

100 Hessian modes will be used to form the next step
Hessian Eigenvalues:
-0.618034 -0.399765 -0.016600 0.020658 0.368189 0.732183
0.959980 0.984071 0.999855 0.999983 0.999998 1.000000
1.000000 1.000000 1.000000 1.000000 1.000000 1.000000
1.000000 1.000000 1.000000 1.000000 1.000000 1.000000
1.000000 1.000000 1.000000 1.000000 1.000000 1.000000
1.000000 1.000000 1.000000 1.000000 1.000000 1.000000
1.000000 1.000000 1.000000 1.000000 1.000000 1.000000
1.000000 1.000000 1.000000 1.000000 1.000000 1.000000
1.000000 1.000000 1.000000 1.000000 1.000000 1.000000
1.000000 1.000000 1.000000 1.000000 1.000000 1.000000
1.000000 1.000000 1.000000 1.000000 1.000000 1.000000
1.000000 1.000000 1.000000 1.000000 1.000000 1.000000
1.000000 1.000000 1.000000 1.000000 1.000000 1.000000
1.000000 1.000000 1.000000 1.000000 1.000000 1.000000
1.000000 1.000000 1.000000 1.000000 1.000000 1.000000
1.000000 1.000000 1.000000 1.000000 1.000754 1.006686
1.608179 1.618058 2.551248 3.696678

4 constraint modes removed due to symmetry

ERROR Something Wrong in Assigning Constraint modes

Q-Chem fatal error occurred in module 0, line 9:

OPTIMIZE fatal error

#2

Seems like your symmetry flags (SYMMETRY = TRUE but SYM_IGNORE = TRUE) are in conflict, for one thing. You should decide if you want symmetry or not, probably “not” is the better option here. I also think that all of the constraints should be put into a single $opt section.

Be forewarned that optimizations using a lot of FIXED atom constraints can be very slow to converge because those constraints force the use of Cartesian coordinates. The fact that the output is referring to “modes” makes me suspect that the 2nd $opt section may not have been read. Generally it’s a bad idea to give the same $input section twice.