  The common sense regarding twisting or untwisting a ribbon is that it
requires the application of an external rotation to happen. However, at
nanoscale, the application of precise amounts of rotation on a nanoribbon is
not a trivial task. Here, the concept of an alternative method to add twist to
or remove twist from a twisted graphene nanoribbon (TGNR) without rotation is
presented. The method consists of suspending a TGNR on two separate substrates
and by changing only their distance, the total amount of twist of the TGNR is
shown to change. The possibility to fine-tuning the amount of twist of a TGNR
is also shown. The concept is demonstrated through fully atomistic molecular
dynamics simulations and numerical calculations of the topological parameters
twist and writhe of a TGNR. It is shown that the above process satisfies the
so-called linking number theorem of space curves. Besides being experimentally
feasible, this concept reveals a new kind of twist to writhe transition
phenomenon that is tension-free and does not require controlling neither the
nanoribbon end-to-end distance nor its critical twist density.
