Calculate magnetic flux generated by 3-D electronic charge

carbon9

Hi,

I'm trying to calculate the magnetic flux generated by a nanowire. I can calculate the 3-D electronic charge and the effective potential (using Siesta 3.0 - a DFT calculator). Having the 3-D electronic charge and effective potential in hand, how can I calculate the (self?) magnetic flux generated by this nanowire?

Thanks in advance...