I have run the program for Counterpoise correction for BSSE, but the program got terminated, saying "The combination of multiplicity 1 and 205 electrons is impossible". How do I solve this issue?
The type of job (NBO, counterpoise etc.) is irrelevant here, as you have an error in the definition of the molecule. The sentence "The combination of multiplicity 1 and 205 electrons is impossible" should be quite obvious - either you are missing some atoms (or have some additional atoms) in the molecule you specified or it's a radical, which should have a different multiplicity.