Hi I'm trying to optimise a molecule by using the b3lyp/6-31G(d) method , the calculus took more than 2 days and the energy never converged .
Here is my input code
%chk=S-21.chk
# opt freq B3LYP/6-31G* SCRF=(PCM,read,solvent=CH2Cl2)
S-21
0 1
C -1.75068100 0.37734700 0.81263500
C -2.62257500 -0.29227700 -0.14373800
C -4.10723100 -0.09641000 -0.01731400
C -4.61852400 0.73486000 1.04941400
C -3.74681500 1.31785500 1.90876500
C -2.31430800 1.13987700 1.79050600
H -5.69934800 0.85871100 1.11964000
H -4.10201200 1.94778900 2.72638200
H -1.68650000 1.64617500 2.52642700
N -4.80498300 -0.74379100 -0.93998600
N -2.28519800 -1.08000700 -1.15378200
S -3.70847600 -1.57391000 -1.94372300
C -0.28701900 0.19538500 0.70641300
C 0.55775500 1.19398300 0.34091700
C 0.21097700 -1.14867100 0.99271500
C 2.05755400 0.97694800 0.39853600
C 1.50838800 -1.47640300 0.80224900
H -0.52454700 -1.88180100 1.32139800
C 2.47232700 -0.47418800 0.32746700
C 0.10593100 2.52300100 -0.07746100
C 0.93014100 3.38020900 -0.71164500
C 2.31062000 3.02195300 -1.00934000
C 2.84013300 1.86879500 -0.54543500
H -0.93897900 2.77149900 0.10783000
H 0.59157200 4.36097200 -1.04420600
H 2.87715100 3.70674700 -1.63618300
H 2.36087800 1.32019000 1.44439100
C 4.20468100 1.44278400 -0.87492700
C 4.61668300 0.17803800 -0.66911800
C 3.71092200 -0.82964300 -0.11389200
H 4.85713200 2.19281800 -1.32106100
H 5.62508700 -0.14589500 -0.92529400
C 4.14879800 -2.22396900 -0.04913700
C 1.99749300 -2.88270200 1.03166300
C 3.36272400 -3.17101600 0.48626400
H 5.13572700 -2.45364800 -0.44739700
H 1.27197900 -3.60363700 0.58826800
H 1.99321400 -3.09445600 2.12663400
H 3.67769000 -4.21084800 0.55589600
radii=UAKS
Here is the errors that I got
Error termination request processed by link 9999.
Error termination via Lnk1e
Information about geom opt convergence
Item Value Threshold Converged?
Maximum Force 0.043390 0.000450 NO
RMS Force 0.003584 0.000300 NO
Maximum Displacement 0.044852 0.001800 NO
RMS Displacement 0.004028 0.001200 NO
Here is the output structure (the bond between C(16)-H(27) 16 got broken) I don't know how to fix these issues