Constrained optimisation

%mem=720MB
%chk=prtOpt_1.chk
#p opt=(modredundant,maxcycle=50) freq=internalmodes b3lyp/6-31g(d) nosymm
5d

partial optimisation

0 1
 B                 -1.23658400    0.37875000   -0.11005500
 C                 -2.40052500    0.14722200   -1.18648900
 C                 -4.31986400   -0.44154500   -3.19074700
 C                 -3.54500600   -0.63226200   -0.90876500
 C                 -2.25476000    0.62231900   -2.50269300
 C                 -3.19686500    0.33425500   -3.49237800
 C                 -4.49668300   -0.92152000   -1.89240000
 H                 -3.74268200   -0.95864100    0.11361600
 H                 -1.38066900    1.22224300   -2.74247700
 H                 -3.05695800    0.71477800   -4.50123900
 H                 -5.37562300   -1.51013300   -1.64215900
 Zn                -1.55434900   -2.29216500   -0.27833700
 C                 -2.33974100    1.31518300    1.48677700
 H                 -3.28924900    1.82707200    1.28181900
 H                 -2.58645200    0.26209500    1.63031900
 C                 -2.00784500   -4.05326300   -0.88461700
 H                 -2.87347100   -4.45038300   -0.34273700
 H                 -1.17853000   -4.75479400   -0.74397600
 H                 -2.00601900    1.63026600    2.49187600
 H                 -2.26109700   -4.03831800   -1.95003000
 Zn                -0.98132400    2.63744000    0.60786000
 Zn                 1.14330500   -0.08025100    0.16808600
 O                 -0.12905300    1.21305500   -0.44537400
 C                  2.92350200   -0.77015400    0.44834000
 H                  3.18739200   -1.51823000   -0.30851900
 H                  3.67767000    0.02279200    0.39946300
 H                  3.01060600   -1.25035000    1.42959900
 C                 -0.60920000    4.54188000    0.72405600
 H                 -1.28343400    5.10895800    0.07065500
 H                 -0.73714600    4.93271000    1.74005900
 H                  0.41643900    4.76747000    0.40948200
 O                 -0.74415800   -0.84101100    0.48761100
 C                 -5.36104489   -0.75629280   -4.28091955
 F                 -5.88358389    0.39655398   -4.75038445
 F                 -6.34600007   -1.51614543   -3.75652725
 F                 -4.76627385   -1.42520215   -5.29151724

1 F
13 F

Comments to the input

Constrained optimisations are useful when trying to find good starting points for a subsequent transition state search. An optimisation is constrained by adding the option "modredundant" to the keyword "opt". After the molecule specification the atoms, bond lengths, angles, or dihedral to be frozen are specified. In the example above atoms 1 and 13 are frozen.