COMB3 - single point calculation (fixed optimisation)

To Whom It May Concern,

I would like to run fixed nanocluster structure optimisation with COMB3 potential (relaxation/optimisation with fixed atomic coordination).

Which command do I have to insert to do the fixed (constrained) structure optimisation.

Here is the input file which I used for general global optimisation with COMB3

it is not clear what you are asking here. if you want to keep atoms immobile during minimization, you can use fix setforce. an atom will not move during minimization if its force is set to zero.