Optimise in the prescence of an electric field

Questions
#1

Hi everyone,
I am trying to optimise a system in the prescence of an electric field. I need my axis to not reorient in the calculation and I am freezing one coordinate. My input file is:
$comment
bgly polar M11/cc-pVTZ
$end

$molecule
0 1
C 1.05181 -0.00076 0.43357
C -1.97623 0.56913 2.59397
N -0.69851 0.04854 3.19252
O 1.41782 -0.03775 1.65523
C 2.22206 -0.16084 -0.55077
O -0.10195 0.10126 -0.02954
C -3.00701 0.85576 3.71241
N 3.46925 -0.64839 0.14350
O -2.44484 0.86337 4.85602
O -4.20337 0.99241 3.36869
H -2.33038 -0.18272 1.88499
H -1.72442 1.50027 2.07929
H -0.81888 -0.92690 3.45369
H -0.61366 0.56663 4.08226
H 0.13963 0.15604 2.58871
H 1.99676 -0.88242 -1.33993
H 2.47198 0.81096 -0.98526
H 3.36336 -1.64028 0.37889
H 3.45742 -0.16347 1.05964
H 4.33598 -0.46773 -0.36356
$end

$rem
JOBTYPE OPT Optimization
METHOD M11 Dispersion-corrected hybrid functional
BASIS cc-pVTZ Basis Set
SCF_MAX_CYCLES 50000 500 scf cycles
GEOM_OPT_DMAX 150 Maximum Stepsize
NO_REORIENT TRUE DO not reorient the axis
SYM_IGNORE TRUE Do not reorient
$end

$opt
FIXED
1 X
2 X
3 X
4 X
5 X
6 X
7 X
8 X
9 X
10 X
ENDFIXED
$end

$multipole_field
X 0.0
Y 0.0
Z 15.0
$end

problem is, my carbonyl bond breaks every time. Any idea why?

#2

Not sure what you are trying to accomplish here with a large set of constraints (which often makes optimization problematic) and a VERY large electric field (15 a.u.). The terminal CO2 is pulled off at the HF/6-31G* level also. I think you should experiment with a more affordable SCF method and a smaller electric field, to get your bearings.

#3

The typical chemically relevant electric fields are at most a couple of hundreds of MV/cm. In Q-Chem, the units of multipole fields are in a.u., and 1 au = 5142 MV/cm. An electric field of 15 au will cause many unexpected issues (e.g., bond breaking events).