x3dna_ensemble is not working for hairpin loop structures made up of only one strand as for pdb id '2n4l' which contains multiple models. When this file is being processed by x3dna_ensemble, it is prompting the message :
> x3dna_ensemble analyze -e 2n4l.pdb -b bp_order.dat
Process model #1 1 / 10
Not a duplex: <>
I tried this for other loop structures too. Please check this. If i am doing something wrong kindly inform me.
Best,
Sudhanshu Shanker