# Which mechanics or law is predominately seen on the nanoscale?

Nanotechnology and sciences are the study or the manipulation of matter on an atomic, molecular, and supramolecular scale especially at nano meter range. We know that at macro molecular level a system can be described using Newtonian/classical mechanics (eg: $F=ma$) whereas for an electronic level quantum mechanics are used. In nanotechnology and science which mechanics is seen predominantly; is it Newtonian, quantum or both and why?

• Seems like a nice essay topic for HW... what are your thoughts? – DrMoishe Pippik Jul 3 '15 at 1:30
• I dont know whether this answer is correct but after searching a while came across this site and its about planck length. the scale at which classical mechanics become invalid and quantum mechnaics comes into effect. So we can confirm that at nano scale its between Newtonian mechanics or an intermediate of newton-quantm mechanics – Eka Sep 4 '15 at 3:11
• Quantum mechanics dominates by the very definition of the nanoscale. "Nano" is essentially just a buzz-word for "quantum". Classical methods can be used for supramolecular aggregates, but just as a rather crude approximation and only for the reason that the application of quantum mechanics to such relatively big systems is yet too expansive. – Wildcat Nov 11 '15 at 9:33

## 1 Answer

Its depence on the size of the system your are looking at. To understand spectroscopy of molecules, you usually use quantum mechanics. In molecular dynamics simulation, you'll need both: On the one hand, there is a potential needed based on QM-interactions, on the other hand, the classical equations of motion are good enought to move your atoms in a QM-force field.

Based on your problem, you have to decide how much classical mechanics you can justify. But in the nanoscale everything is made up with quantum mechanics and classical mechanics are used to approach a problem, which is not solvable in quantum mechanic way in an accetable periode of time.