How to derive bulk modulus with the Birch Murnaghan equation of state?
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Merel on 16 Jul 2015
Answered: Nick Hobbs on 21 Jul 2015
Currently I am doing some molecular modeling to calculate the bulk modulus of different materials. However, I am not very familar with fitting specific equations to a datafile. I need to fit the Birch Murnagan equation of state to the Volume-Energy data:
E(V) = E_0 + ((9*B_0*V_0)/16) * ((V/V_0)^(2/3)-1)^2*(6+B'_0((V/V0)^(2/3)-1)-4*(V/V_0)^(2/3))
How can I fit the curve to the equation without rewriting the complete EOS equation to E = Ax^3 + Bx^2 + Cx + D?
Nick Hobbs on 21 Jul 2015
Assuming you only need to fit your function to a dataset, one way to fit your equation is with the function fit from the Curve Fitting Toolbox. There is a provided example where they use a custom model. In your case, you could use your equation as an anonymous function like the provided example, and use the function to fit your data to your provided equation.
Find more on Curve Fitting Toolbox in Help Center and File Exchange
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