# Concept of Elasticity on an atomic level

1. Oct 23, 2009

### RohansK

Hi guys,
Can someone explain The concept of ELASTICITY on an atomic level.

To be clear can somebody please try and elaborate on how does a metal rod or bar or wire start to extend under the influence of an external load.

What exactly happens on the interatomic level, say we consider ( for the purpose of ease and understanding) a single layer of atoms ( a horizontal line of atoms 0-0-0-0-0-0-0-0-0) where 0 is an atom and - inidcates the seperation between two consecutive atoms) and a load applied at one end on the first atom and the last atom is fixed into a support like a wall.

Then How exactly will the atoms behave and how actually will the interatomic seperation increase between two consecutive atoms, how will the interatomic restoration forces influence them and their forward movement ie increase in seperation.

What will be the position of two consecutive atoms wrt each other ( for the first pair for eg.) at a particular instant of time ie the distance between them and the forces acting on them.
Say that the first atom is pulled by the applied load then as it starts to move forward due to the pull the seperation between it and the second atom increases. Then how exactly the forces will be developed between it and the second atom and how will these forces increase /decrease ( wrt the PE v/s Distance graph) on each others. How will the distances, interatomic seperations and speeds of each of them keep changing wrt time say from the start to the complete deformation reached and the condition of the above parameters for each of the atoms at a few intervals of time from start to end.

Though it may not come very close to reality Can anyone give a very crude estimation to visualise this ( it may be simply an rough analogy just to try to understnad the whole thing at atomic level)

Or can you suggest some books on the ELASTICITY which handles the subject at atomic level explainations or close to it. So as to get a better picture of whats going on inside than just taking for granted the Hookes Law and deformation and the equations of elasticity.

Thanks and Regards.

2. Oct 23, 2009

### Mapes

Re: Elasticity

Atoms in unstrained solids are spaced at a distance that corresponds to a minimum energy; when we elastically deform the material, this distance changes and energy increases, producing a restoring force. The interaction is often modeled at a simple level as a http://en.wikipedia.org/wiki/Lennard-Jones_potential" [Broken]. Take a look at Callister's introductory book on materials science for more information.

Last edited by a moderator: May 4, 2017