Hi, I am new to ORCA and am struggling to freeze the Pi bonds of the molecule because it keeps moving. I currently using the ORCA 5.0.4. I tried to do a metal doping Heptazine with an Iron atom, and every time I did geometry optimization, I observed that the pi bond moved. Is there a possible way to freeze the pi bond? The text below is my codes for the simulations.

# avogadro generated ORCA input file

# Advanced Mode

# Geometry Opt of Heptazine-Fe molecule

! B3LYP OPT def2-TZVP def2/J NormalPrint defGrid2 PAL4

* xyz 0 2

N 0.27248 0.36480 0.00000

C -0.88189 1.09238 0.00000

N -0.82531 2.44790 0.00000

C 0.37776 3.07876 0.00000

N 1.52835 2.35659 0.00000

C 1.47974 1.00077 0.00000

C 0.21959 -0.99870 0.00000

N -2.08037 0.45656 0.00000

C -2.13042 -0.90095 0.00000

N -0.98260 -1.62747 0.00000

N 2.62537 0.27402 0.00000

C 2.57010 -1.08329 0.00000

N 1.36945 -1.71871 0.00000

H -3.08709 -1.40488 0.00000

H 3.48486 -1.65982 0.00000

Fe 0.45718 5.12592 0.00000

*

I hope you help me. Thank you