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General Questions and Answers / Re: Youngs modulus for buckyball
« on: January 2, 2017, 17:50 »
It is still a tricky case because enclosing it in a bulk configuration does not make it a bulk system, for which you can calculate a well-defined stress tensor.
One possibility is that you optimize the buckyball, calculate the stress, then strain the cell in one direction, calculate the stress again and then get the Young's modulus as
(stress_strained - stress_unstrained)/strain
Note that the stress is normalized to the volume of the cell, which is arbitrary, so you have to correct the stress for the actual volume of the buckyball.
How you define that volume depends very much on what you want to do with the Young's modulus.
One could think of using the volume of a sphere with the same diameter as the buckyball, but you really need to think carefully yourself, whether this fits your application.
I have attached an example script which assumes the volume of a solid sphere.
Please remember again, that there is no real straightforward definition for the Young's modulus in your system, and we can only give you one possible auxiliary way to estimate a quantity, which could be used as a Young's modulus, but you should carefully review whether this makes sense in your application!
One possibility is that you optimize the buckyball, calculate the stress, then strain the cell in one direction, calculate the stress again and then get the Young's modulus as
(stress_strained - stress_unstrained)/strain
Note that the stress is normalized to the volume of the cell, which is arbitrary, so you have to correct the stress for the actual volume of the buckyball.
How you define that volume depends very much on what you want to do with the Young's modulus.
One could think of using the volume of a sphere with the same diameter as the buckyball, but you really need to think carefully yourself, whether this fits your application.
I have attached an example script which assumes the volume of a solid sphere.
Please remember again, that there is no real straightforward definition for the Young's modulus in your system, and we can only give you one possible auxiliary way to estimate a quantity, which could be used as a Young's modulus, but you should carefully review whether this makes sense in your application!