Calculating Young Modulus to GPa

[saray1360]

Hi,

I have calculated the young modulus of a system by calculating the second derivate of the energy against the axial strain and then I devided the result on the volum.

The unit of the energy is eV and the volume is in angstrom^3. I want to calculate the young modulus in GPa, should I consider a coefficient? how could I get to GPa out of [eV/(angS^3)] ?

Regards,

 

[tiny-tim]

convert to SI

Hi saray1360!

Pa is an SI unit, so you need to convert everything else to SI units first.

angstrom is easy … but eV is totally non-SI, so you'll need to find the factor to convert it to joules.

 

[nlightner]

Thank you for your question. The young modulus is a measure of the stiffness of a material and is typically measured in units of Pascals (Pa) or Gigapascals (GPa). In order to convert your calculated value from eV/(angstrom^3) to GPa, you will need to use a conversion factor. The conversion factor for eV to Pa is 1 eV = 1.602 x 10^-19 J, and 1 angstrom = 10^-10 m. Therefore, the conversion factor from eV/(angstrom^3) to GPa would be 1.602 x 10^-19 J/(10^-10 m)^3 = 1.602 x 10^-3 GPa. This means that you can simply multiply your calculated value by 1.602 x 10^-3 to obtain the young modulus in GPa. I hope this helps. Let me know if you have any further questions.