How to compute and output stress of a Carbon chain that exists in fluid?

Dear all,

I simulated a Chain of carbon atoms in a fluid (water). I need to caclulate the strain/ stress and Young Modulus of the Chain. In order to do that I applied forces to the top, bottom and Center of the chain such that summation of forces and torques are zero, so the chain does not move in the environment as the result of forces. ( I can not use the fix deform as I just want to calculate the Chain stress not the whole system).

My question is how do I compute and output the stess and strain?

are “compute stress” and “fix print” , the commands I need to use? if yes, reading the document I have a hard time figuring out how to print the stress computed in my system.

Thank you so much.