Dear All, I am in a fix (i) as to how to draw the VD- ID, VG-ID etc. by kwant coding. I am to some extent clear to get those relations from the back calculations of G= ID/VG and the current expression in terms of the G. Finding G by kwant they may be found out. But, I like very much a direct coding technique to get these curves. (ii) as to how to visualize a 3D graphics of nanostructure like QWR, QD which I visualize in 2D without problem. Please help me. Best Wishes. K.K.Ghosh