I get the final defect energy value with my code . But it comes with a caution “too many failed attempts to optimise”
In this case , can I consider this value or not ?
Kindly let me know
This is where you have to use your scientific judgement. If the Gnorm is close to zero then it may be OK, but usually it means you need to fix something. Typically poor optimisation behaviour means that your force field is not smooth - there are discontinuities in the potential energy surface, which optimisers can’t cope with since they assume the surface is continuous. Increasing cutoffs or tapering potentials to zero can improve things (or look out for bond breaking forming if using molecular functionality).