My system is a 6,6-single walled carbon nanotube with both ends terminated with hydrogens. When define, I used the default eht parameters. Then i give the molecular charge as zero. A message is shown: WARNING. HOMO-LUMO ENERGY GAP LOWER THAN 0.05!!!!
So,what should I do? Should I reject the default occupation or accept the default and use fermi during optimization....please give me suggestion.